The present study was carried out to investigate the protective role of garlic (Allium sativum) ethanol extract (GE) in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced hepatic and testicular toxicity. A total of 60 male rats (Sprague-Dawley, weighing 200 +/- 10 g) were divided into six equal groups. The normal control group (NC) received vehicle (intraperitoneally) and saline (perorally). A predetermined dosage of TCDD (40 mu g/kg of body weight, i.p.) was administered to single TCDD-treated (TT) and test (GE) groups. GE was administered (perorally) at daily doses of 5 (GE5), 10 (GE10), 20 (GE 20), or 40 (GE40) mg/kg of body weight for 5 weeks, starting 1 week before the TCDD exposure. Decreases in body weight gain (P < .01) and testicular weight (P < .01) induced by TCDD were greatly attenuated by GE (P < .05-.01). TCDD-induced decreases in spermatogenesis-related panels-Johnsen's score, seminiferous tubular size, ratio of tubules with sperm, and sperm count/tubule-were greatly improved by GE treatment in a dose-dependent manner in the rats. TCDD-induced increases in serum cholesterol and triglyceride levels and glutamic oxaloacetate activity were also suppressed by GE (P < .05-.01). These results indicate that administration of garlic to TCDD-exposed rats attenuates testicular and hepatic damage, suggesting that garlic might be a useful agent that can protect human health from toxic responses induced by environmental pollutants.