| M.O.S.T. (Mothers Of Super Twins) | |
| M.O.S.T. (Mothers Of Super Twins) - Twins and Triplets | |
MA | |
| MAB Community Services | |
| MAB Community Services - Blind / Visually Impaired | |
| MAD DADS, Inc. | |
| MAD DADS, Inc. - Parenting / Grandparenting | |
| MADD (Mothers Against Drunk Driving) | |
| MADD (Mothers Against Drunk Driving) - Crime Victims / Offenders | |
| MAGIC Foundation for Children's Growth | |
| MAGIC Foundation for Children's Growth - Short / Tall | |
| Maine Parent Federation | |
| Make-A-Wish Foundation | |
| Make-A-Wish Foundation - Wish Granting for Ill Children Helpline | |
| Male Chronic Pelvic Pain Network | |
| Male Chronic Pelvic Pain Network - Prostate Problems | |
| Male Survivor: National Organization Against Male Sexual Victimization | |
| Male Survivor: National Organization Against Male Sexual Victimization - Sexual Abuse / Incest / Rap | |
| MaleBC | |
| MaleBC - Breast Cancer | |
| Malignant Hyperthermia | |
| Malignant Hyperthermia Association of the U.S. (MHAUS) | |
| Malignant Hyperthermia Association of the U.S. (MHAUS) - Malignant Hyperthermia | |
| Man To Man Program | |
| Man To Man Program | |
| Man To Man Program - Cancer | |
| Man To Man Program - Prostate Problems |  Top |
| Mannosidosis, Alpha | |
| Maple Syrup Urine Disease | |
| Maple Syrup Urine Disease Family Support Group | |
| Maple Syrup Urine Disease Family Support Group - Maple Syrup Urine Disease | |
| March of Dimes | |
| March of Dimes - Health Helpline | |
| Marden-Walker Syndrome | |
| Marfan Syndrome | |
| Mariensco-Sjogren Syndrome Support Group | |
| Mariensco-Sjogren Syndrome Support Group - Marinesco-Sjogren Syndrome | |
| Marijuana Anonymous World Services | |
| Marijuana Anonymous World Services - Drug Abuse | |
| Marine Moms Online | |
| Marine Moms Online - Veterans / Military | |
| Marinesco-Sjogren Syndrome | |
| Marriage / Family | |
| Marrow Transplants Helpline | |
| Mastocytosis | |
| Mautner Project, the National Lesbian Health Organization | |
| Mautner Project, the National Lesbian Health Organization | |
| Mautner Project, the National Lesbian Health Organization - Cancer | |
| Mautner Project, the National Lesbian Health Organization - Sexual Orientation / Gay and Lesbian | |
MC | |
| McCune-Albright Syndrome | |
| McCune-Albright Syndrome/Fibrous Dysplasia Division | |
| McCune-Albright Syndrome/Fibrous Dysplasia Division - McCune-Albright Syndrome | Top |
ME | |
| Meat and Poultry Hotline | |
| Meat and Poultry Hotline - Food Handling / Food Co-Op Helpline | |
| Medical Escrow Society | |
| Medical Escrow Society - Life-Threatening Illness Helpline | |
| Medicare + Choice Helpline Assistant | |
| Medicare + Choice Helpline Assistant - Health Helpline | |
| Membranoproliferative Glomerulonephritis Type II | |
| Men for Sobriety | |
| Men for Sobriety - Alcohol Abuse | |
| Men's Issues | |
| Mended Hearts | |
| Mended Hearts - Heart Disease | |
| Meningitis Foundation | |
| Meningitis Foundation - Meningitis Helpline | |
| Meningitis Helpline | |
| Menkes Kinky Hair Syndrome | |
| Menkes Kinky Hair Syndrome - Menkes Kinky Hair Syndrome | |
| Menstuff | |
| Menstuff - Men's Issues | |
| Mental Health (General) | |
| Mental Health Association | |
| Mental Health Association | |
| Mental Health Association - Clearinghouse - California | |
| Mental Health Association - Clearinghouse - Ohio | |
| Mental Health Association of East Tennessee | Top |
| Mental Health Association of East Tennessee - Clearinghouse - Tennessee | |
| Mental Health Association of Monroe County | |
| Mental Health Association of Monroe County - Clearinghouse - New York | |
| Mental Health Consumers | |
| Mental Health Helpline | |
| Mental Retardation / Down Syndrome | |
| Mental Retardation Helpline | |
| Messies Anonymous | |
| Messies Anonymous - Messiness | |
| Messiness | |
| Metabolic Disorder Helpline | |
| Metabolic Disorders | |
| Metatropic Dysplasia Dwarf Registry | |
| Metatropic Dysplasia Dwarf Registry - Metatropic Dysplasia Dwarfism | |
| Metatropic Dysplasia Dwarfism | |
| Methadone Anonymous Support | |
| Methadone Anonymous Support - Drug Abuse | |
MH | |
| MHE and Me: A Support Group for Kids with MHE | |
| MHE and Me: A Support Group for Kids with MHE - Multiple Hereditary Exostoses | |
MI | |
| Military / Veterans Helpline | |
| Miller's Syndrome | |
| Minority Health Resource Center | |
| Minority Health Resource Center - Health Helpline | |
| Miracle Flights for Kids | |
| Miracle Flights for Kids - Transportation Helpline | Top |
| Missing Children/Adults Helpline | |
| Mitochondrial Disorders | |
ML | |
| ML4 Foundation | |
| ML4 Foundation - Mucolipidosis Type 4 | |
MO | |
| Mocha Moms, Inc. | |
| Mocha Moms, Inc. - Parenting / Grandparenting | |
| Moderation Management | |
| Moderation Management - Alcohol Abuse | |
| Moebius Syndrome | |
| Moebius Syndrome Foundation | |
| Moebius Syndrome Foundation - Moebius Syndrome | |
| Molesters Anonymous | |
| Molesters Anonymous | |
| Molesters Anonymous - Crime Victims / Offenders | |
| Molesters Anonymous - Sexual Abuse / Incest / Rape | |
| MOMS Club | |
| MOMS Club - Parenting / Grandparenting | |
| MOPS, International (Mothers Of Pre-Schoolers) | |
| MOPS, International (Mothers Of Pre-Schoolers) - Parenting / Grandparenting | |
| Mothers and More | |
| Mothers and More - Parenting / Grandparenting | |
| Mothers From Hell 2 | |
| Mothers From Hell 2 - Parents of Disabled / Ill Children | |
| Mothers of Freshmen | |
| Mothers of Freshmen - Parenting / Grandparenting | Top |
| Mothers Supporting Daughters with Breast Cancer | |
| Mothers Supporting Daughters with Breast Cancer - Breast Cancer | |
| Motility Disorders | |
MP | |
| MPD-Net | |
| MPD-Net - Myeloproliferative Disease | |
MS | |
| MS Moms (Managing Our Multiple Sclerosis) | |
| MS Moms (Managing Our Multiple Sclerosis) - Multiple Sclerosis | |
| MSL Help | |
MU | |
| Mucolipidosis Type 4 | |
| Mucopolysaccharidoses / Morquio's Syndrome | |
| Mullerian Anomalies of the Uterus | |
| Mullerian Anomalies of the Uterus - Women's Health | |
| Multiple Endocrine Neoplasia Society (MENS) | |
| Multiple Endocrine Neoplasia Society (MENS) - Multiple Endocrine Neoplasm Type I | |
| Multiple Endocrine Neoplasm Type I | |
| Multiple Hereditary Exostoses | |
| Multiple Myeloma | |
| Multiple Sclerosis | |
| Multiple Sclerosis Association of America | |
| Multiple Sclerosis Association of America - Multiple Sclerosis | |
| Multiple Sclerosis Foundation | |
| Multiple Sclerosis Foundation - Multiple Sclerosis Helpline | |
| Multiple Sclerosis Helpline | |
| Multiple Symmetrical Lipomatosis | |
| MUMS National Parent-to-Parent Network | Top |
| MUMS National Parent-to-Parent Network | |
| MUMS National Parent-to-Parent Network - Networking for Ill / Disabled | |
| MUMS National Parent-to-Parent Network - Parents of Disabled / Ill Children | |
| Muscular Dystrophy | |
| Muscular Dystrophy Association | |
| Muscular Dystrophy Association - Muscular Dystrophy | |
| Muscular Dystrophy Family Foundation, Inc. | |
| Muscular Dystrophy Family Foundation, Inc. - Muscular Dystrophy Helpline | |
| Muscular Dystrophy Helpline | |
| Musella Foundation | |
| Musella Foundation - Brain Injury / Brain Tumor / Coma | |
MY | |
| Myasthenia Gravis | |
| Myasthenia Gravis Foundation of America, Inc. | |
| Myasthenia Gravis Foundation of America, Inc. - Myasthenia Gravis | |
| Myasthenia Gravis Patient-To-Patient | |
| Myasthenia Gravis Patient-To-Patient - Myasthenia Gravis | |
| Mycosis Fungoides | |
| Mycosis Fungoides UK | |
| Mycosis Fungoides UK - Mycosis Fungoides | |
| Myelin Disorders | |
| Myelodysplastic Syndromes Foundation | |
| Myelodysplastic Syndromes Foundation - Anemia | |
| Myeloproliferative Disease | |
| MyMolarPregnancy.com | |
| MyMolarPregnancy.com - Death of a Child / Fetal Loss | Top |
| Myositis | |
| Myotonia Congenita | |
| Myotonia Congenita - Myotonia Congenita Forum | |
| Myotonia Congenita Forum | |
| Myotubular Myopathy | |
| Myotubular Myopathy Resource Group | |
| Myotubular Myopathy Resource Group - Myotubular Myopathy | |
