Dominant lethal studies were conducted in SD male rats with 5 halogenated 3-carbon compounds that are structurally similar to a known mutagen 1,2-dibromo-3-chloropropane (DBCP). 1,2,3-Tribromopropane induced dominant lethal mutation especially in the early spermatid stage. This finding was almost the same as that obtained after DBCP treatment. The estimated dominant lethal mutation index of a group treated with 1,2-dibromopropane was marginal at week 1 of testing. On the other hand, bromopropane, 1,2,3-trichloropropane and 1-chloropropane produced negative responses for induction of dominant lethals.