It has been reported that G009, polysaccharide isolated from Ganoderma lucidum IY009 has various pharmacological effects, such as antinflamatory, antiviral, anticarcinogenic and immunmodulation effects. The purpose of this study was to determine the subacute toxicity of orally administered G009 in Sprague-Dawley rats. Groups of 40 male and 40 female rats were gavaged with 0, 500, 1,000 or 2,000 mg/kg/day for 30 days. No drug-related deaths and clinical morbidities were resulted. There was no drug-related effect on the body weight gain, food consumption and water consumption. Statistically significant changes were observed in several hematological and biochemical parameters of G009-treated groups; however, most of these changes were within normal range and had no relationship to dosage. Urinalysis and bone marrow biopsy showed no remarkable changes in all treated groups. Gross necropsy and hisopathology revealed no evidence of specific toxicity related to G009. Our data indicate that no-observed effect level of G009 is estimated to be above 2,000 mg/kg/day in rats.