Reovirus type 1, strain Lang (1/L), can infect hepatocytes in vivo only after hepatocellular damage is induced by hepatotoxins, surgical trauma, resection, or profound immunosuppression. To examine the role of cell cycle and cellular differentiation on liver cell susceptibility to reovirus infection, a murine hepatocarcinoma cell line, Hepa 1/A1, was infected with reovirus and assayed for the presence of infectious virus or reovirus antigen in cells. Despite a > 95% binding of reovirus to hepatocarcinoma cells as indicated by cytometric analysis; only 10% of hepatoma cells contained infectious virus by infectious center assay. In comparison, 100% of L cells were infected. Analysis of intracellular reovirus antigen revealed its presence in dividing but not in quiescent hepatocytes. This correlation of cellular division and cell capacity to support viral replication suggests that induction of hepatocyte proliferation may be a mechanism for liver susceptibility to reovirus infection.