Objective To investigate the incidence and distribution of fetal discrepancy during the first trimester in dichorionic twins.Methods This was a prospective analysis of dichorionic twin pregnancies that underwent 11+0～ 13+6 week scan at a tertiary hospital from Sep 2008 to Oct 2010.Differences in crown-rump length (CRL),nuchal translucency ( NT),heart rate ( HR).deepest vertical pockets of amniotic fluid (DVP) for every pair of twin fetuses were calculated and expressed as absolute value and percentage of discordance.Results A total of 66 dichorionic twin pregnancies were included.The average CRL was significantly different between the larger fetus and the smaller one,which were (65.28 ±8.54)mm and (62.34 ± 8.49) mm respectively ( P ＜ 0.001).The average NT was significantly different between two fetuses,which were ( 1.56 ± 0.35) mm and (1.28 ± 0.30) mm respectively. HR and DVP were also statistically different between two fetuses ( P ＜0.001).Conclusions The growth of two fetuses in normal dichorionic twins is not uniform during the first trimester.