The subacute toxicity of combined antibiotics, SP-102 (Sulbactam·Piperacilline), was examined in S.D.rats. Four groups of rats were administered intraperitoneally with 0, 512, 1280 and 3200 mg/kg/day of SP-102 for 30 days. Main clinical sign related to the compound was soft stool. The body weight gain was slightly decreased in male rats treated with 1280, 3200 mg/kg and in female rats treated with 1280 mg/kg of SP-102. Water consumption was significantly increased in rats administered with SP-102. There were no dose-related changes of urinalysis, biochemical examination and hematological findings in all the groups treated with SP-102. Gross necropsy and histopathology revealed no evidence of specific toxicity related to SP-102. Our data indicate that no-observed effect level of SP-102 is below 512 mg/kg in male and female rats. Maximum tolerated dose of SP-102 was estimated to be above 3200 mg/kg in this study.