Objective: Resistin is a potent regulator of glucose homeostasis which is thought to oppose the action of insulin in peripheral tissues. The aim of this study was to determine changes in resistin levels in gestational diabetes mellitus (GDM). Material and Method: Twenty women with GDM (mean age 32.28 ± 5.01 years old, and gestational age 32.2 ± 4.8 weeks) matched with 22 non diabetic pregnant women (NGDM) (mean age 30.30 ± 4.5 years old, and gestational age 34.8 ± 3.5 weeks) were included in the study. Body mass index (BMI) was calculated. Serum resistin levels were measured and insulin resistance was calculated with HOMA-IR. The Mann Whitney U test was used for statistical analysis. Results: BMI was 33.8 ± 6.2 kg/m2 in the GDM group and 28.4 ± 6.2 kg/m2 in the NGDM group (p = 0.04). Serum resistin levels were 8.7 ± 2.1 ng/ml in the GDM group and 8.1 ± 2.5 ng/ml in the NGDM group. Mean resistin level was not different between the two groups. HOMA-IR in GDM was higher than in the NGDM group (13.2 ± 12.2 vs 5.8 ± 5.1, p = 0.02, respectively). Conclusion: Although mean BMI in GDM was higher than in NGDM and insulin resistance in GDM was more marked than in NGDM, serum resistin levels in GDM were not found to be any different from NGDM.