The effects of personal hygiene, sexual history, diet, and stress on the risk of vulvovaginal candidiasis were estimated from a case-control study of students attending a public university during 1986-87. Data from medical records and self-administered questionnaires were used to compare 85 cases to 1,245 other students using the Health Service, and to 113 subjects chosen from the total student population. Frequent sexual intercourse was the strongest risk factor (seven or more times a week versus none): OR = 4.3; 95% CI: 1.4, 12.9 (for cases versus Health Service controls).