It has been reported that human cytomegalovirus (HCMV) induces activation of infected cells. The potential of HCMV to activate quiescent cells was investigsted indirectly by using drugs that inhibit cell proliferation. Several known antimetabolic anticancer drugs such as 6-thioguanine, 5-fluorouracil, ara-C and papaverine were chosen for this purpose. The antimetabolic anticancer drugs as well as papaverine inhibited the proliferation of human fibroblasts and the multiplication of HCMV with varing efficiency at or lower than the highest nontoxic concentrations. Among these 6-thioguanine and papaverine were found to reduce the level of HCMV yields in a dose-response manner and potent inhibitors of HCMV multiplication. Removal of these drugs from media reversed the block of HEF cell proliferation and HCMV multiplication by the drugs. Therefore the data suggest a possible correlation between cell proliferation and HCMV multiplication in human fibroblasts.