The aim of the study was to correlate intra-observer reproducibility of the nuchal translucency measurements by two-dimensional and three-dimensional transvaginal ultrasound. Examinations were performed on 120 women undergoing ultrasound screening at 10 to 14 weeks' gestation. They were examined by two experienced ultrasonographers using both methods two times consecutively. Statistical analysis for the assessment of intra-observer reproducibility was paired t-test. Nuchal translucency measurements were obtained in 100% of cases with three-dimensional sonography compared to only 85% with two-dimensional sonography. Better intra-observer reproducibility was obtained for three-dimensional than for two-dimensional ultrasound. Three-dimensional transvaginal ultrasound improves accuracy of nuchal translucency measurement allowing appropriate mid-sagittal section of the fetus and clear distinction of the nuchal region from the amniotic membrane.