To evaluate the genotoxicity of SKP-450, an antihypertensive agent the in vitro reverse mutation assay using Salmonella typhimurium, the Chromosome aberration assay using Chinese hamster lung (CHL) cells and the in vivo micronucleus assay using bone marrow cells of ddY mice were performed. In the Reverse mutation test, SKP-450 did not induced mutagenicity in Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537 with and without metabolic activation. In the chromosome aberration assay using CHL cells, there was no increased incidence of structural and numerical aberrations with and without metabolic activation. The in vivo induction of micronuclei was measured in polychromatic erythrocytes of bone marrow of male ddY mice at 30 hours after treatment with SKP-450 by p.o once. The results showed no increased incidence of micronucleated polychromatic erythrocytes in bone marrow of ddY male mice treated with SKP-450.