We report on an infant, born to a diabetic mother, who presented with hypocalcemia and congenital heart disease, presurgically diagnosed by echocardiography as truncus arteriosus type I. Cytogenetic analysis showed a 45,X,-Y,-22,+der-(Y)t(Y;22) (p11.3q11.2) chromosome abnormality with del(22)(q11.2). Parental chromosomes were normal. Autopsy showed persistent truncus arteriosus type II and thymic aplasia consistent with DiGeorge anomaly. This report adds to the existing literature demonstrating an association between DiGeorge anomaly and monosomy 22q11.