Pregnancy in patients with gestational diabetes mellitus (GDM) is associated with increased perinatal morbidity. Whether the perinatal mortality rate, particularly the fetal death rate, is greater in these patients remains controversial. The present study was undertaken to review the role of antepartum fetal monitoring in 69 patients with GDM controlled by diet only (class A) and 28 women requiring insulin therapy (class AB). Hypertension complicated 21.6% of these pregnancies. Antepartum fetal surveillance included outpatient nonstress testing, urinary estriol assays, maternal assessment of fetal activity, and clinical estimation of fetal weight. All insulin-requiring patients as well as fourteen class A patients with identifiable risk factors underwent testing. No perinatal deaths occurred. Only six patients required intervention for suspected fetal jeopardy and four of these women had hypertension. Macrosomia was correctly identified in only 6 of 16 infants weighing 4000 g or more. This study suggests that, in GDM, an outpatient program of fetal testing, using primarily the nonstress test and maternal assessment of fetal activity, can be employed in patients requiring insulin as well as class A patients with identifiable risk factors. This protocol resulted in a low rate of unnecessary intervention and good perinatal outcome. The risks for abnormal antepartum testing results appear increased in GDM with hypertension and prolonged pregnancy.