Abnormal genitalia was a salient clinical finding in two unrelated male infants with the hydantoin embryopathy syndrome. Both infants also exhibited hypoplastic nails of fingers and toes, hypertelorism, and a flat nasal bridge, and one had severe developmental retardation. We review previously reported cases of the hydantoin embrypathy syndrome and discuss factors possibly affecting the teratogenicity of phenytoin. Male infants with findings such as the patients of this report need to be differentiated from patients with Noonan syndrome and Aarskog syndrome. We suggest that mothers receiving phenytoin who have given birth to one affected infant should be given a different anticonvulsant for future pregnancies.