We studied the effect of two cytokines, basic fibroblastic growth factor (bFGF) and transforming growth factor beta (TGF-beta) on human cytomegalovirus (HCMV) replication in cultured human lung fibroblasts. We show that TGF-beta increases HCMV production, probably by a transcriptional mechanism, and that bFGF represses HCMV replication in a dose-dependent manner. These actions were antagonistic and the mechanisms involved were independent of the effects of these factors on cell DNA synthesis and proliferation.