1. This report is based upon a systematic, clinical study of a group of consecutive women discharged from the hospital with the diagnosis of uncomplicated hyperemesis gravidarum compared to a group of consecutive controls selected by taking the next admission to the hospital of a normal, full-term, uncomplicated pregnancy in the same ward or private status.2. The study involved a personal clinical interview with each woman 2 to 4 years after discharge from the hospital: 84% of the original sample were found and interviewed; 94% of the women who remained within 250 miles of the hospital were found and interviewed. We thus studied 69 vomiters and 66 controls.3. The interviews were clinical in their orientation and covered the following areas: medical and psychiatric symptoms, past illnesses, operations, hospitalizations, socioeconomic status, pregnancies, nursing, contraception, marital and sexual adjustment, relations with mothers and mothers-in-law, and personal psychologic adjustment. Each area was systematically covered in the same order in each woman.4. There were no significant differences between vomiters and controls with respect to overall psychiatric illness nor with respect to any individual psychiatric illness.5. There were no significant differences between vomiters and controls with respect to other gastrointestinal symptoms, menstrual disorders or psychologic symptoms.6. There was no evidence that the prevalence of hyperemesis gravidarum was higher in women from upper socioeconomic levels.7. There were no significant differences between vomiters and controls with respect to primiparity, abortions and still births, contraception, attitudes toward and planning for pregnancy and nursing, separation and divorce, trouble with husband, sexual adjustment and relations with mothers and mothers-in-law.8. Vomiters were significantly more likely to vomit with other pregnancies than were controls.9. There were no significant differences between vomiters and controls to suggest that there is any association between hyperemesis gravidarum and chronic psychiatric or psychologic disorders.