In a colony of black and white ruffed lemurs, Lemur (Varecia) variegatus subsp., similar congenital anomalies were found in successive years. Four malformed infants had skull defects, scoliosis, kinked tails, internal anomalies as well as reduced birth weights. The derived from one male and two females whose phenotypes are normal except for the kinked tail of the male. The possible causes including modes of inheritance are considered.