1. The reverse mutation test was carried out on propiverine hydrochloride (P-4) at dose range of 5-500 μg/plate using Salmonella typbimurium strains, TA100, TA98, TA1535 and TA1537, and Escbericbia coli strain WP2uvrA. -As compared with so1vent-treated control, no significant increases were observed in the number of revertant colonies in all tester strains in both systems with and without mammalian metabolic activation (S9 Mix). 2. The chromosomal aberration test was also carried out on P-4 using cultured Chinese hamster lung cells (CHL). The cells were treated with P-4 at the doses of 5, 10, 20 and 40 μM without S9 Mix and at 62.5, 125, 250 and 500 μM with S9 Mix. No significant differences were found in the incidence of structural- and numeral-aberrations of chromosomes in both systems with and without S9 Mix. 3. These rebults indicate that P-4 has no mutagenic activity.