Intraperitoneal administration of zinc chloride in vivo at 14 μg/g body weight (equivalent to 1/2 LD50) over a 3 week period induced an increase in liver weight. The mean weight of the livers in zinc-treated C57/6J mice was 50%higher than that of control animals. Image analysis revealed a concomitant and significant increase in the cross-sectional area and perimeter of the hepatocytes in the zinc-treated group. The mean cross-sectional area of hepatocytes in the zinc-treated mice was 337.2±4.3 μm² as compared to 224.6±2.9 μm² in the control group (p<0.05, Mann-Whitney test). The mean perimeter, of hepatocytes in zinc-treated mice was 72.4±0.5 μm as compared to 58.9±0.4 μm in control animals (p<0.05). It would appear that subacute administration of zinc may result in increase in liver mass due to hypertrophy of the hepatocytes.