Administration of cadmium chloride (1.0 mg/kg s.c.) to rats, twice a day for 7 days, significantly stimulated the activities of hepatic pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-diphosphatase and glucose 6-phosphatase, markedly increased the concentration of hepatic cyclic adenosine monophosphate and circulating blood glucose and significantly reduced serum insulin levels. Furthermore, subacute exposure to cadmium induced glucose intolerance that was associated with a decreased pancreatic secretory activity as evidenced by lowered insulinogenic indices and marked inhibition of phentolamine-stimulated insulin release. In contrast to cadmium, administration of selenium dioxide (2 X 1.0 mg/kg/day s.c., 7 days) failed to alter significantly the activities of gluconeogenic enzymes, hepatic cyclic adenosine monophosphate, blood glucose or serum insulin levels, glucose tolerance or the pancreatic secretory activity. However, administration of selenium concurrently with cadmium completely prevented the cadmium-induced increases of hepatic gluconeogenic enzymes. Treatment with selenium ameliorated the cadmium-induced hyperglycemia, hypoinsulinemia, glucose intolerance and the suppression of pancreatic secretory activity, whereas it failed to alter significantly the cadmium-induced elevation of hepatic cyclic AMP levels. Data provide evidence suggesting that subacute exposure to cadmium alters several parameters of carbohydrate metabolism and suppresses pancreatic secretory activity and that administration of selenium alone is without any appreciable effect on the above parameters. However, administration of selenium concurrently with cadmium prevents, to varying degrees, several of the cadmium-induced metabolic and functional changes.