Holoprosencephaly (HPE), a complex brain malformation resulting from incomplete cleavage of the prosencephalon into distinct cerebral hemispheres, is rare in newborns. Two preterm male neonates were born at 34 weeks’ and five days’ gestation in the monochorionic diamniotic twin pregnancy complicated with pre-eclampsia and intrahepatic cholestasis of pregnancy, and one of them was prenatally diagnosed with alobar HPE by ultrasonography with frontal bossing, hydrocephaly, hypotelorism of eyes, flat nasal bridge, macroglossia, and cheilo/palatoschisis at birth. Karyotyping by G-banding of amniocentesis specimens in normal twin and fetal umbilical blood in both fetuses showed 46, XY. This report expands discordant alobar holoprosencephaly in monochorionic diamniotic twins.