Subacute vanadium toxicity was investigated in rats. Female Wistar strain rats, weighing 180g (approximately 6 weeks old), were divided into three groups of seven each. They were fed a base diet with addition of various concentrations of vanadium (0, 50 or 100ppm) for 10 weeks. The amounts of vanadium found in kidney and liver increased in response to vanadium exposure. A significant increase in metallothionein (MT) was observed in kidney of both the 100ppm and 50ppm vanadium-fed groups. Significant decreases in hemoglobin, hematocrit and leukocyte counts were also observed in the former, as well as decreased lymphocyte counts, B cells and immunoglobulin G and M levels.