The mutagenic activities of N-nitrosobis(2-hydroxypropyl)amine (BHP) and its related compounds were studied in Salmonella typhimurium TA100 and TA98 strains by Ames's liquid incubation assay in the presence or absence of lung and liver S9 of rats treated with polychlorinated biphenyl (PCB). BHP and its related compounds, N-nitroso-(2-hydroxypropyl)(2-oxopropyl)amine (HPOP), N-nitrosobis(2-oxopropyl)amine (BOP), N-nitrosobis(2-acetoxypropyl)amine (BAP), and N-nitroso-2,6-dimethylmorpholine (NDMM) showed negative mutagenicity in the absence of lung and liver S9 in TA100 and TA98 strains while those compounds showed positive in the presence of liver S9 in TA100 strain. HPOP and BOP showed positive mutagenic activity in the presence of lung S9 in TA100 strain. HPOP showed the strongest mutagenic activity in the presence of lung and liver S9.