Truncal duplication represents one of the rare forms of conjoined twins. We
observed a male infant with a truncal duplication; in the host twin no pat
hology was found except an atrial septal defect and a large omphalocele. Th
e parasitic twin was attached to the xiphoid region (xiphopagus) in an oppo
site and "horseriding" manner, was acephalic, and had multiple gastrointest
inal, genitourinary, and skeletal anomalies. The junction site consisted of
lipoid and muscular structures. Surgical separation was done without any d
ifficulty. The abdominal defect was repaired primarily. The host twin is do
ing well.