OBJECTIVE: To compare the outcome of twin pregnancies after in-vitro fertilization (IVF) with that of spontaneously conceived twins. METHODS: We analyzed 146 twins retrospectively, who had been delivered between January 2000 and July 2005. After reviewing their obstetric medical records, 72 twins conceived with IVF (IVF group) and 51 spontaneously conceived twins (spontaneous group), whose gestational age was over 24 weeks, were recruited for this study. RESULTS: There were no significant statistical differences of demographic features such as maternal age, gestational age and fetal weight between the two groups. However, the risk of pregnancy-induced hypertension (PIH) and gestational diabetes (G-DM) had significantly increased in the group of IVF (OR 2.59; 95% CI 1.01~6.66). The risk of fetal weight discordancy rate (>20%) and fetal-sex homology rate in IVF group were decreased (OR 0.37; 95% CI 0.14~0.96, OR 0.45; 95% CI 0.21~0.99). CONCLUSION: In this comparative study, maternal PIH and G-DM risks of IVF group are higher than that of spontaneous group. But, fetal-weight discordancy risk and fetal-sex homology rate were lower in IVF group.