The effects of aluminum (Al) exposure on reproductive functions of male rats were investigated. Forty male Wistar rats (4 weeks old) weighing 75-95 g were randomly divided into four groups and orally exposed to 0 (control group GC), 64.18 (low-dose group GL), 128.36 (middle-dose group GM), and 256.72 (high-dose group GH) mg/kg aluminum trichloride in drinking water for 120 days. The levels of testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were determined by radioimmunoassay. The androgen receptor (AR) expressions in testes were detected respectively by immunohistochemistry and time quantitative PCR. Results showed that the levels of T and LH in GM and GH were lower than those in GC (P < 0.05), but there were no significant changes in FSH level in all Al-treated groups (P > 0.05). AR protein expressions in GM and GH were lower than those in GC (P < 0.05), and there was a dose-response relationship between Al-exposure doses and AR protein expressions. The levels of AR mRNA expressions were lower in all Al-treated groups than those of GC (P < 0.05). The results indicate that Al can cause endocrinal disorders and interfere with AR expression, which suppresses development and functional maintenance of the testes.