Lead poisoning is an old but persistent public health problem in developing countries. The present study investigated blood lead levels and its effects on markers of renal function and parameters of erythrocyte oxidative stress in adolescent male auto repair workers in Turkey. Blood Pb level and the ALAD index ( logarithm of activated delta-aminolaevulinic acid dehydratase/ nonactivated delta-aminolaevulinic acid dehydratase) were measured as indicators of exposure to Pb. Markers of tubular damage urine N-acetyl-beta-D-glucosaminidase (NAG), beta(2)-microglobulin (beta-2 MG), creatinine (Cr), uric acid (UA), and calcium, markers of glomerular filtration blood urea nitrogen ( BUN), serum Cr, UA, and parameters of oxidative damage in erythrocyte were studied in 79 Pb-exposed adolescent and 71 healthy control subjects. Blood lead levels and ALAD index were found significantly higher in the study group than that of normal control group. BUN, UA level, and glomerular filtration rates were detected in normal range in the lead-exposed group. Urinary NAG excretion and calciuria were higher in the study group than in controls. Urinary excretion of NAG was positively correlated with the blood lead levels ( r = 0.427). There was no relationship between blood lead levels and UA or beta-2 MG in urine. Malondialdehyde and glutathione peroxidase levels were significantly elevated in lead-exposed adolescents than controls, but changes in the catalase and superoxide dismutase activities in lead-exposed adolescents did not reach statistical significance. In conclusion, chronic low-dose lead exposure seems as a cause of subtle renal impacts in adolescent workers of auto repair workshops. Lead-induced oxidative stress in erythrocytes probably contributes to these subclinical renal effects.