The ability of cumene to induce mutations at the gene locus coding for hypoxanthine-guanine phosphoribosyl transferase in Chinese hamster ovary cells (CHO/HGPRT Assay) was evaluated in the presence and absence of metabolic activation from Aroclor-induced rat liver S9 fraction. Based on preliminary cytotoxicity tests, nonactivated cultures were treated with cumene at concentrations of 8, 16, 32, 64, and 128 mcg/ml producing cell survivals relative to the vehicle control (Pluronic F127) of 122.9, 92.8, 104.7, 124.6, and 89.2% respectively. Activated cultures treated with cumene concentrations of 64, 128, 150, and 175 mcg/ml produced relative cell survivals ranging from 91.0 - 7.6%. A significant mutagenic response was not observed in either activated or nonactivated trials.