Several studies indicated that pancreatic beta-cell death occurs in both type 1 and type 2 diabetes. This experimental study was designed to determine the effect of gestational diabetes on the beta-cells in 16-week-old rat offspring. By this aim, adult Wistar rats aged 10-12 weeks were randomly allocated in control and diabetic groups. The diabetic group received 40 mg/kg/body weight of streptozotocin (STZ) on day zero of gestation. After delivery, diabetic offspring of GDM mothers and controls at the age of 16 weeks were sacrificed and pancreases harvested and fixed. The number of beta-cells and were counted by Gomori's method staining. Also, apoptosis in pancreas tissue of diabetic and control offspring was detected by TUNEL assay. Results showed a significant reduction in beta-cell number in offspring of GDM (p<0.05). TUNEL assay showed that the number of apoptotic cells increased in GDM compared to controls (P<0.05). This study revealed that gestational diabetes induces pancreatic beta-cells apoptosis in 16-week-old rat offspring.