As shown in the previous studies, asymmetric dimethylarginine (ADMA) is related to endothelial dysfunction, whereas high-sensitive C-reactive protein (hCRP) is the marker of inflammation. In our study, we investigated ADMA, hCRP, and homocysteine concentrations in women with gestational diabetes mellitus (GDM) and normal glucose tolerance (NGT) during late pregnancy. Fifty-four women with GDM and 69 women with NGT between 32 and 39 weeks of gestation were included in this study. ADMA, hCRP, homocysteine, lipid parameters, glycated hemoglobin (HbA1c) levels, insulin, and homeostasis model assessment for insulin resistance (HOMA-IR) were measured. The plasma ADMA concentrations were significantly higher in GDM patients than in NGT subjects (P = 0.03) and the hCRP levels were also significantly increased in GDM group when compared with those in the NGT group (P = 0.008). However, plasma homocysteine levels did not differ between the groups (P = 0.4), while HOMA-IR, insulin, and triglyceride levels were higher in the GDM group than in the NGT group (P = 0.001, 0.002, and 0.02, respectively). The ADMA concentrations in the third trimester were positively correlated with the glucose levels the 50-g glucose challenge test (GCT) during 24-28 weeks in the whole group (r = 0.21, P = 0.02). Our results demonstrate that ADMA and hCRP are elevated in women with GDM during late pregnancy. Further studies are needed to clarify the significance and the underlying mechanisms of the elevated ADMA and hCRP levels in women with GDM.