Two sisters had low birth weight dwarfism, psychomotor retardation, and congenital anomalies including hyperextensible joints, brachydactyly, clinodactyly, low total ridge counts, bilateral simian creases, and calcaneovalgus foot deformities. In addition, both girls had repeated bacterial infections and elevated serum IgA levels. The older sister had no immune response to intradermal antigens and did not develop a protective level of diphtheria antitoxin following two series of diphtheria and tetanus toxoids and pertussis vaccine injections and three Schick tests. These sisters represent a newly described genetic syndrome, most probably an autosomal recessive trait.