Glucocorticoids are commonly used in various clinical conditions. But its use is often associated with adverse effects, including insulin resistance, hyperinsulinemia and hyperglycemia. The objective of the present study was to measure the median effective dose (ED50) of dexamethasone to induce hyperinsulinemia in wistar rats. Graded doses (0.0625, 0.125, 0.25, 0.5, 1, 2, 4, 8 and 16mg/kg) of dexamethasone were administered intraperitoneal (i.p.) to male wistar rats for 6 days (n=6). On the last day of experiment, serum insulin and glucose levels were measured. ED50 value was calculated by plotting log-dose response curve. The maximum effect of dexamethasone on insulin levels was observed in 8mg/kg and minimum effect was observed in 0.0625mg/kg dexamethasone. There was no further increase in response at 16mg/kg dexamethasone in rats. Significant increase in glucose levels were observed only with higher doses (0.5, 1, 2, 4, 8 and 16mg/kg) of dexamethasone. We concluded that median effective dose (ED50) of dexamethasone was 1.8mg/kg or 1800μg/kg for inducing hyperinsulinemia. This dose is preferable for detecting the efficacy and potency of insulin sensitizers as well as to screen drug effects which may reduce or increase insulin resistance.