Medical Organizations
- National Federation of Licensed Practical Nurses (NFLPN)
- National Federation of the Blind (Canada) (NFB)
- National Fertility Center (NFC)
- National Foundation for Asthmatic Children (NFAC)
- National Foundation for Infantile Paralysis (NFIP)
- National Foundation for Metabolic Research (NFMR)
- National Foundation for Neuromuscular Diseases (NFND)
- National Gastroenterological Association (NGEA)
- National Guild of Hypnotists (NGH)
- National Health and Medical Research Council (NHMRC)
- National Health Association (UK) (NHA)
- National Health Service (NHS)
- National Hearing Conservation Association (NHCA)
- National Heart and Lung Institute (NHLI)
- National Heart Institute (NHI)
- National Heart, Lung, and Blood Institute (NHLBI)
- National Hemophilia Foundation (NHF)
- National Honor Society (NHS)
- National Institute for Health and Clinical Excellence (NIHCE)
- National Institute for Nuclear Science and Technology (INSTN)
- National Institute for Occupational Safety and Health (NIOSH)
- National Institute of Agricultural Botany (NIAB)
- National Institute of Allergy and Infectious Diseases (NIAID)
- National Institute of Arthritis and Metabolic Diseases (NIAMD)
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMSD)
- National Institute of Child Health and Human Development (NICHHD)
- National Institute of Dental Research (NIDR)
- National Institute of Diabetes & Digestive & Kidney Diseases (NIDDKD)
- National Institute of Environmental Health Services (NIEHS)
- National Institute of First Assisting (NIFA)
- National Institute of General Medical Sciences (NIGMS)
- National Institute of Industrial Psychology (NUP)
- National Institute of Medical Research (UK) (NIMR)
- National Institute of Mental Health (NAMH)
- National Institute of Mental Health (UK) (NIMH)
- National Institute of Neurological and Communicative Disorders (NINCD)
- National Institute of Neurological Diseases and Blindness (NINDB)
- National Institute of Neurological Diseases and Stroke (NINOS)
- National Institute of Nursing Research (NINR)
- National Institute of Radiological Sciences (NIRS)
- National Institute on Aging (NIA)
- National Institute on Deafness and Other Communication Disorders (NIDOCD)
- National Institute on Drug Abuse (NIDA)
- National Institutes of Health (NIH)
- National Joint Practice Commission (NJPC)
- National Kidney Foundation (NKF)
- National League for Nursing (NLN)
- National League for Nursing Education (NLNE)
- National Library of Medicine (NLM)
- National Malaria Society (NMS)
- National Medical and Dental Association (NMDA)
- National Medical Association (NMA)
- National Medical Center (NMC)
- National Medical Service (UK) (NMS)
- National Multiple Sclerosis Society (NMSS)
- National Naval Medical Center (NNMC)
- National Neurological Research Foundation (NNRF)
- National Nosocomial Infections Study (NNIS)
- National Nursery Examination Board (UK) (NNEB)
- National Nurses United (NNU)
- National Ophthalmic Treatment Board (NOTB)
- National Optometric Association (NOA)
- National Organization for Human Services (NOHS)
- National Organization for Public Health Nursing (NOPHN)
- National Organization for Rare Disorders (NORD)
- National Organization of Hospital Schools of Nursing (NOHSN)
- National Osteopathic Foundation (NOF)
- National PACE Association (NPA)
- National Pharmaceutical Association (NPA)
- National Pharmaceutical Services Association (NPSA)
- National Physicians Alliance (NPA)
- National Psychological Association for Psychoanalysis (NPAP)
- National Quality Forum (NQF)
- National Radiological Protection Board (UK) (NRPB)
- National Register of Health Service Psychologists (NRHSP)
- National Research and Development Corporation (NRDG)
- National Research Council (NRG)
- National Rheumatoid Arthritis Society (NRAS)
- National Rural Health Association (NRHA)
- National Science Foundation (NSF)
- National Security Council; National Safety Council (NSC)
- National Society for Crippled Children (NSCC)
- National Society for Epilepsy (NSE)
- National Society for Medical Research (NSMR)
- National Society for the Prevention of Blindness (NSPB)
- National Society of Compliance Professionals (NSCP)
- National Society of Denture Prosthetics (NSDP)
- National Society of Genetic Counselors (NSGC)
- National Strength and Conditioning Association (NSCA)
- National Student Nurses' Association (NSNA)
- National Student Speech Language Hearing Association (NSSLHA)
- National Technical Information Service (NTIS)
- National Tuberculosis Association (NTA)
- National Upper Cervical Chiropractic Association (NUCCA)
- Naturopathic Medicine Committee (NMC)
- Naturopathic Medicine Institute (NMI)
- Naval Medical Research Institute (NMRI)
- Nebraska Chiropractic Physicians Association (NCPA)
- Nebraska Counseling Association (NCA)
- Nebraska Optometric Association (NOA)