Selenium is an essential trace element and a component of various enzymes with antioxidant functions. High-sensitive C-reactive protein (hsCRP) is an early indicator of increased lipid peroxidation. The serum selenium concentration, lipid parameters, and hsCRP values of gestational diabetic pregnant women (GD), control pregnant women (CP), and healthy nonpregnant controls (HC) were compared. Blood was taken between the 24th and the 28th week of pregnancy when the oral glucose tolerance test was performed. Selenium concentration was determined by atomic absorption spectrometry after hydride generation. HsCRP was measured by immunturbidimetry. HC had significantly higher serum selenium concentrations than GD and CP women (HC = 77.4 +/- 14.82, GD = 51.7 +/- 11.62, and CP = 40.5 +/- 8.03 microg/l, respectively). HsCRP values of both GD and nondiabetic pregnant women were significantly higher compared to controls. Significant negative correlations were found between serum selenium and total cholesterol, low-density lipoprotein cholesterol, and hsCRP values indicating that low selenium levels are associated with increased lipid peroxidation. Serum selenium concentrations of Hungarian pregnant women are low compared to internationally published data.