OBJECTIVES: To compare the perinatal mortality and morbidity of infants born from monochorionic versus dichorionic twin pregnancies (TP). PATIENTS AND METHODS: Retrospective, comparative study of monochorionic and dichorionic TP over 10 years in the south of Reunion Island. Information regarding demographic, gestational and perinatal variables of mothers and infants was collected from the hospital perinatal database. RESULTS: Six hundred and twenty dichorionic and 155 monochorionic TP were analyzed. In case of monochorionic TP, mothers had higher rates of pregnancy-related hypertension (OR=1.82, 95%CI=[1.02-3.29] ; P=0.03) and hospitalization (OR=1.48, 95%CI=[1.02-2.16]; P=0.03). Newborns from monochorionic TP had higher morbidity for : very preterm birth (birth before 33 weeks gestation) (OR=1.65, 95%CI=[1.02-2.66]; P=0.02), very low birth weight (birth weight\textless1500g) (OR=1.73, 95%CI=[1.57-3.13]; P\textless0.001), Apgar\textless7 at 1 minute (OR=1.76, 95%CI=[1.18-2.61]; P\textless0.01) and hospitalization (OR=2.08, 95%CI=[1.58-2.73]; P\textless0.001). Perinatal mortality was also significantly higher (OR=2.47, 95%CI=[1.54-3.94]; P\textless0.001), as well intrauterine fetal death (OR=3.96, 95%CI=[1.95-8.05]; P\textless0.001) CONCLUSION: This study confirms that few differences exist among dichorionic and monochorionic TP with regard to maternal morbidity, while neonatal morbidity and mortality are higher in twins born from monochorionic pregnancies.