To examine whether the medical school environment is important in influencing students to choose careers in primary care, the authors in 1991 compared certain characteristics of the environments of schools that produced high percentages of primary care physicians with those of schools that produced low percentages over a five-year period. The authors used the American Medical Association Physician Masterfile to identify the percentage of graduates of each of 121 medical schools for the period 1981-1985 who entered primary care specialties. They then compared the 25 schools that produced low percentages (22-29%) with the 25 schools that produced high percentages (39-56%). The results demonstrate important differences between the two groups of schools in their commitments to primary care education, their research programs, and their clinical environments supporting required clerkships. The authors conclude that a school's educational environment is an important factor in influencing some students to pursue careers in primary care medicine.