The present study investigates the testicular and adrenocortical activities under different doses and durations of chromium (Cr) exposure and their interactions. Mature male Sprague Dawley rats were injected daily with three different doses (0.2, 0.4, and 0.6 mg/kg bw) of Cr salt (K2Cr2O7) intraperitonealy for 13 and 26 days, respectively. The medium (0.4 mg/kg bw/day) and higher dose (0.6 mg/kg bw/day) of Cr significantly (p < 0.05) decrease accessory sex organs weight, testicular Δ53β-hydroxysteroid dehydrogenase (HSD) and 17β-HSD activities, epididymal sperm count, effective spermatid degeneration, serum testosterone, LH level, testicular catalase and superoxide dismutase (SOD) activities while testicular lipid peroxidation, serum FSH, corticosterone level, adrenal weight and adrenal Δ53β-HSD activity increased significantly than that of control and lower dose (0.2 mg/kg bw/day) Cr exposed animals. Testicular histoarchitechture shows deterioration after critical dose (0.4 mg/kg bw/day) and duration (26 days) of Cr exposure. Cr induced alterations on testicular and adrenocortical activities are dose and duration dependent. Adrecortical hyperactivity accompanied by testicular oxidative stress might have a crucial role for Cr induced male reproductive impairment. © 2007 Elsevier Inc. All rights reserved.