To compare the incidence, severity and pregnancy outcomes of pregnancy induced hypertension in twins and singleton gestations.The cohort study enrolled 305 twins and 298 singleton gestations at Department of Obstetrics and Gynaecology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand between January 1996 and December 2001. The rates of pregnancy induced hypertension and pregnancy outcomes were statistically analysed in both groups. P-value of< 0.05 was considered statistically significant.Pregnancy induced hypertension was found to at develop 18.36% in the twin gestations, compared with 5.03% in the singleton gestations (P < 0.05). Women with twin gestations had higher rates of pregnancy induced hypertension (RR 3.65, 95% CI 2.11-6.30, P<0.05) and occurred earlier than singleton gestations (35.86+/-2.50 VS 37.40+/-1.18 weeks, P<0.05). Twin gestations with pregnancy induced hypertension had significantly higher rate of cesarean delivery, low birthweight, NICU admission and perinatal death than singleton gestations with pregnancy induced hypertension (P< 0.05). Moreover the abruptio placenta, postpartum hemorrhage and perinatal mortality in twin gestations with pregnancy induced hypertension group were significantly higher than in normotensive group (P< 0.05).The incidence of pregnancy induced hypertension was significant higher and occurred earlier with greater adverse pregnancy outcomes among twin gestations than singleton gestations. Moreover, the rate of adverse maternal and perinatal outcomes in twin gestations with pregnancy induced hypertensive group was higher than in normotensive group.