Introduction: Gestational Diabetes Mellitus (GDM) is glucose intolerance diagnosed for the first time in pregnancy. It may lead to potentially serious short term and longterm complications for both mother and fetus or newborn. Material and Methods:Prospective study was conducted at the University clinic for gynecology and obstetrics, Skopje for the period of one year. 100 pregnant women in the second trimester which performed oral glucose tolerance test (75g OGTT) were evaluated. The study included 50 women with GDM and control group of 50 women with negative OGTT at the same gestational age, parity and maternal age. Gestational weight gain, blood pressure and urine analysis for proteinuria were recorded monthly. Patients with GDM were more often followed according to the clinical protocol. Maternal and neonatal data was collected after birth from medical records during discharge from the clinic. The perinatal outcome of pregnant women with or without GDM was analysed.Results: There was a significant difference in BMI between the women with GDM and normoglycemic women. Hypertensive disorders of pregnancy, preterm labour and delivery by caesarean section were significantly more often in GDM pregnancies vs control group. Respiratory distress, hypoglycemia, pH <25, lower Apgar score in the first minute and admission in the neonatal intensive care unit was significantly more often in the neonates from mothers with GDM vs controls. Conclusion:Many parameters of the perinatal outcome were significantly associated with GDM in our study. Adequate treatment can achieve better maternal and neonatal outcome.