Background and Objective: Gestational diabetes mellitus (GDM) complicates 3-5% of all pregnancies. Glucose Challenge Test (GCT) is a universal screening test for GDM between 24-28 of gestation. Plasma glucose is measured 1 hr after ingestion of 50g glucose load. The aim of this study was to determine the relationship of plasma lipids in 13-23 weeks of pregnancy with abnormal GCT (Glucose Challenge Test). Materials and Methods: This prospective longitudinal study was carried out during 2010-2011. The subjects comprised 575 pregnant women aged 18-35 years old who had referred to two health centers (Kosar and Shahid Soleymani) in Shahr rey –Tehran. The subjects were followed until their 24-28 weeks of gestation. Maternal plasma lipid concentrations were measured at 13-23 weeks of gestation and then all participants were screened at 24-28 weeks of gestation with GCT. A value over 140mg/dl in GCT was considered positive. Results: Logistic Regression analyses confirmed that triglyceride (TG) concentration (OR=1.005, 95% CI= 1.001-1.010) associated with abnormal GCT. No evidence of association was found between GCT risk and plasma concentrations of other lipids (i.e., total cholesterol, high-density lipoprotein and low-density lipoprotein). In ROC curve analysis, the TG cut-off point in abnormal GCT was 142.5 mg/dl (with 61.3% sensitivity, 60.1% specificity, 73% PPV and 74.63% NPV). Conclusion: The findings of this study imply that TG level at 13-23 weeks of pregnancy can be considered as a predictor factor for abnormal GCT.