[INTRODUCTION - Author describes ultrasonographic twin peak sign in order to differentiate dichorial-diamniotic from monochronic-diamnotic pregnancy in early gestation. In case of dichorial pregnancy the chorial tissue is forming a triangle shape. In case of monochorial twins the two amnion layers are forming a ”T” shape. CASE REPORT - The first case represents a dichorionic pregnancy, while the second case is an example of monochorionic placental formation. CONCLUSION - The twin peak sign has clinical significance, because dichorionic pregnancies carry less risk of gestational and labor complications.]