Background: Diabetes mellitus (DM) is a group of metabolic disorders such as DM I, DM II, secondary causes of DM and gestational diabetes mellitus characterized by hyperglycemic phonotype. The etiology of gestational diabetes mellitus is unknown. Recent studies address the chronic activity of immune system against infections (not autoimmunity) as an important cause of gestational diabetes mellitus. This study aimed to compare T-helper cells 1 and 2 cytokines and associated antibodies in patients with gestational diabetes mellitus and normal pregnant women. Methods: This cross-sectional study was performed on 45 female patients with GDM and 45 healthy pregnant women in Bandar Abbas, Iran, from 2008- 2009. The exclusion criteria were presence of any infectious diseases or autoimmune disorders such as SLE or RA. Present and past medical histories were taken from the participants thorough physical examination. Blood samples (10 mL) were drawn and sent to laboratory for measuring serum IgE, IgG1, IgG2, IgG3, IgG4, interleukin-10 (IL-10), interleukin-12 (IL-12), transforming growth factor-beta (TGF 1), and interferon-gamma (IFN ) measurements. T-test and Kolmogorov-Smirnov test were used for data analysis. Results: The mean age of the patients with GDM and healthy pregnant women was 32.5 and 27.9 yrs, respectively. T-helper 1 and 2 associated antibodies and cytokines had no significant differences between the case and control groups. Conclusion: The changes in T-helper 1 and 2 associated antibodies and cytokines are not associated with gestational diabetes mellitus and could not be considered as a predictor for gestational diabetes mellitus.