The previously unreported combination of bilateral absence of thumbs, aplasia of ulna at one and hypoplasia of ulna on the other side, retarded bone age, short stature, microcephaly, micropenis, cryptorchidism, and mental retardation is described in a 5-year-old boy. Having excluded major differential diagnoses, e.g. Fanconi anemia, RAPADILINO syndrome and VACTERL association, we hypothesize that this boy represents a new multiple congenital anomaly/mental retardation (MCA/MR) syndrome.