Normothermic ischemia of kidney within 1 hr caused critical impairments in metabolic reactions of nephrons. Activities of glucose-6-phosphate and lactate dehydrogenases in erythrocytes may characterize the functional state of kidney tissue in ischemia. Amount of 2,3-glucose diphosphate in erythrocytes correlated with the diuresis level. Kidney tissue ischemia led to alteration in the ratio of young and old erythrocyte populations in circulation. Alterations in activity of glucose-6-phosphate and lactate dehydrogenases in urine occurred due to both an increase in kidney clearance and the impairment of kidney tissue.