Growing male rats were fed dietary Pirimiphos-methyl at 0, 500, 1000 and 1500 ppm for 28 days and selected blood and urine constituents were measured at weekly intervals. Dietary intake of Pirimiphos-methyl induced an initial, transient hypoglycemia and a marked elevation in blood urea at all dosages. Though it did not produce any significant change in the urine output initially, marked oliguria was observed after 12 days of feeding. The alterations observed in urine constituents were: increased urea, proteinuria, transient increase in creatinine and significant increase in the excretion of glucuronic acid and ethereal sulfate at all intervals. However, since no pathological alterations were evident in the kidney, the anomalous urinary excretion of various body constituents might be due to the anticholinesterase action of the insecticide at the central nervous system.