Androgen insensitivity syndrome (AIS) is a disorder of male sexual development caused by an absent or dysfunctional AR. Fertile cases with mild AIS and slightly impaired AR activity had been reported in literature, and their external genitalia were documented to be usually normal or subnormal. We reported here an Arg(840)Cys substitution in the AR gene in a large Chinese pedigree affected with AIS. The mutant gene may result in infertility for some affected males with or without hypospadias. However, it was also observed that the mutation did not affect the fertility of the other patients. The gonadotropin levels for one of these patients were within the normal range. Thus, whether normal levels of the gonadotropins are necessary for the preserved fertility of patients affected with this genetic disorder remains to be elucidated.