At the Royal Free Hospital School of Medicine, London, an integrated course in epidemiology and sociology for preclinical students was introduced in 1979. The course--Population Studies--is taken by the 100 second-year medical students in the summer term before they enter their clinical years. It occupies one full day and one half day each week for 8 weeks--approximately 80 hours of tuition. Population Studies is unusual in two respects. Firstly, it introduces a substantial amount of epidemiology into the preclinical curriculum. And, secondly, this is the only London medical school to integrate the teaching of sociology and epidemiology into the one course.