Y-specific polymorphisms were studied in Gujarati Muslim Indians possessing a Y-chromosome pericentric inversion [inv(Y)] in an attempt to prove a common genetic origin for the inversion. The p49a/TaqI and p49a/PvuII haplotypes were determined for 9 normal and 8 inv(Y) Gujarati Muslim men. Men with the inversion possessed identical TaqI and PvuII profiles, as opposed to 7 different TaqI and 8 different PvuII haplotypes observed in the 9 normal men. These results provide conclusive evidence for a common genetic origin of the inverted Y chromosome observed in this Gujarati Muslim community.