The Nurses' Health Studies (NHS) are long-running, questionnaire-based studies on women's health. The study was initiated in 1976 with the NHS cohort. The initial studies focus on cancer, cardiovascular disease and risk factors for chronic health issues in women. The latest cohort, NH3, has been expanded to include both male and female registered nurses and nursing students. Survey and biospecimen data may be requested by interested researchers.

There a number of study cohorts:

• NHS: Beginning in 1976, this study included 121,700 female registered nurses in the US who were aged 30-55 years old at baseline.
• NHS II: Beginning in 1989, this study included 116,429 female registered nurses in the US who were aged 25-42 years old at baseline.
• Growing up Today Study (GUTS): Beginning in 1996, this study included 27,706 male and female offspring of NHS II participants who were aged 9-14 at baseline.
• GUTS2: Beginning in 2004, the second phase of GUTS included 10,923 children of NHS II participants who were aged 10-17 at baseline.
• NHS3: Beginning in 2010, this study includes over 40,000 male and female nurses and nursing students in the United States and Canada who are at least 19 years old at baseline. Recruitment is ongoing.