The present study was undertaken to investigate the hyperglycemic potential of acute exposure to acephate and its etiology employing rat model system. Oral administration of acephate (140mg/kg b.w.) caused reversible hyperglycemia as evidenced by peak increase in blood glucose at 2h after the administration (87% over control) followed by trend of normalization. In further experiment carried out to understand the etiology of the induced hyperglycemia, we observed that 2h exposure to acephate caused significant increase in blood glucose, plasma corticosterone (78%) and activities of two gluconeogenesis enzymes in liver viz., glucose-6-phosphatase (91%) and tyrosine aminotransferase (84%) compared to that in control. When rats were exposed to acephate for 6h, decrement was observed in elevated levels of blood glucose, plasma corticosterone and the gluconeogenesis enzymes of the liver. Adrenal cholesterol levels in acephate-exposed rats were significantly depleted. While the glycogen content in liver of 2-h exposure group was comparable to control, a tremendous increase in liver glycogen content ( approximately 3.5 folds) was observed in rats of the 6-h exposure group. Our results demonstrate that acephate causes reversible hyperglycemia in rats probably by enhancing hepatic glucose output via gluconeogenesis. A role for hyperactivity of adrenal cortex is suggested in increased gluconeogenesis while significant attenuation in elevated levels of blood glucose and the activity the gluconeogenesis enzyme, glucose-6-phosphatase in liver with concomitant increase in liver glycogen are indicative of the onset of counter-regulatory responses such as hyperinsulinemia, to overcome the induced hyperglycemia.