The obstetric performance and pregnancy outcome in 208 massively obese patients who were delivered over an eight-year period were compared with those of nonobese control subjects. The incidence of obesity in their infants was also compared. No significant increase in the incidence of urinary tract infection, diabetes, breech presentation, cesarean section, forceps delivery, or maternal and infant morbidity was noted in the obese women. Significantly increased incidences of hypertensive disorders of pregnancy (p less than 0.01), gestational diabetes (p less than 0.01), inadequate weight gain (p less than 0.001), and wound or episiotomy infection (p less than 0.05) were observed in the study group. The mean birth weight of the infants of obese women was 209 grams greater than that of the control subjects. A significantly increased number of the obese patients were delivered of excessive-sized infants. Despite this, the incidence of obesity in infants of obese women was not significantly increased at birth or six months of age. By 12 months of age, however, these infants were significantly more obese than the control infants.