Evidence for the relationship between exposures in fetal life, infancy, childhood and early adulthood, and risk of chronic disease in later middle-age continues to accumulate. Further understanding of the associations between exposures acting over the life course and current morbidity and mortality in middle-age and later must depend upon the follow-up of previously established cohorts. This paper describes the design of, and background to, a follow-up of individuals who participated in a survey of student health in the University of Glasgow between 1948 and 1968. 15 332 students, almost a quarter of whom were female, had detailed medical information collected from a doctor-administered questionnaire and physical examination. Participation was voluntary; approximately 50% of the student population took part and these students were rep-resentative of the entire student population. Data collected include: socio-demographic, behavioural, developmental, anthropometric, and clinical details, as well as details of medical history and family health and structure. Data are over 95% complete for most variables. Over 40% of students were examined on two or more occasions with 1026 students (6.8%) having four or more examinations. Over 90% of students were from social classes I-III. Eighty-two per cent (12 533/15 322) of the students have been traced and flagged through the National Health Service Central Register and attempts are on-going to increase this figure. Those study members who have been traced are representative of the original cohort. To date 1111 (7.2%) of those traced have died. These data constitute a unique record of the health and physical development of a large cohort of students from Glasgow. Follow-up to investigate the relationship between indices of health and development, (height, weight, blood pressure), health behaviours and social circumstances in childhood and young adulthood, and mortality and morbidity in later adulthood is under way.