Several polycyclic aromatic hydrocarbons (PAHs) are carcinogenic in rodents, while exposure to these compounds has been associated with various types of human cancer. Engine exhaust and used engine oils are major PAH sources in engine repair workshops. Urinary 1-hydroxypyrene (1-OHP) levels and some genotoxicity parameters (sister-chromatid exchange, SCE; micronucleus, MN) have been compared among engine repair workers (n = 61, age: between 13 and 18) and workers not occupationally exposed to PAH (n = 30, age: between 13 and 19). The mean value (+/- S.E.) of urinary 1-OHP excretions of workers was 4.71 +/- 0.53 micromol/mol creatinine and also mean urinary 1-OHP for controls was found to be as 1.55 +/- 0.28 micromol/mol creatinine. The mean values (+/- S.E.) of SCE frequency per cell in peripheral lymphocytes from the workers and controls were 4.47 +/- 0.09 and 4.06 +/- 0.16, respectively (p < 0.05). The mean (+/- S.E.) MN (per thousand) frequencies in peripheral lymphocytes from the workers and controls were 1.87 +/- 0.04 and 1.56 +/- 0.06, respectively (p < 0.0001). The effect of smoking for the above parameters were also evaluated.