This study sought to understand the effects of vitronectin (VTN) on the growth of SMMC-7721 hepatoma cells. In addition, this study examined how VTN inhibits the induction of apoptosis in SMMC-7721 cells by 3,3'-diindolylmethane (DIM), a metabolite of natural phytochemicals, and preliminarily investigated the signaling molecules involved in this process. A cell proliferation reagent was used to observe the effects of VTN on cell proliferation rates. Laser scanning confocal microscopy was performed to observe the effects of VTN on the morphology of tubulin, a component of the cytoskeleton. Flow cytometry and Western blotting assays were used to observe the inhibitory effects of VTN on DIM-induced apoptosis in SMMC-7721 cells and changes in the expression levels of the signaling molecules involved in this process. VTN promoted tumor cell growth in a concentration-dependent manner and inhibited apoptosis caused by the effects of apoptosis-inducing agents. Under in vitro experimental conditions, VTN contributed to the growth of SMMC-7721 hepatoma cells and protected them from the effects of an apoptosis-inducing agent. These findings suggest that during hepatocellular carcinogenesis, VTN may promote tumor cell growth and inhibit chemically induced apoptosis.