We compared the short-term toxicity of toxic components of aristolochic acid in rats. Twenty-four female Wistar rats were divided into 4 groups and treated orally every 3-days with 10 mg/kg each of aristolochic acid, aristolochic acid-I and aristolochic acid-II for 19 days. After treatment, the relative ratio of liver and kidney weight to body weight, the concentrations of RBC, hemoglobin and hematocrit in the blood, the levels of aspartate amino transferase, alanine amino transferase, alkaline phosphatase, blood urea nitrogen and creatinine in the plasma, and the levels of urinary urea nitrogen and creatinine in the urine were significantly increased. Body weight of rats and the levels of Na+, K+, Ca2+ in the urine were significantly decreased, especially for groups treated with aristolochic acid and aristolochic acid-II. Pathological examination of liver and kidney also showed cell enlargement and lesions, especially for groups treated with aristolochic acid and aristolochic acid-II. The aristolochic acid exhibited significant toxicity, and the short-term toxicity of aristolochic acid-II and aristolochic acid was similar to each other. Renal but not hepatic failure induced by aristolochic acid could be prevented by pentoxifylline.