The effect of exo-polymer from Ganoderma lucidum on the swimming endurance capacity of mice was investigated. The administration of the exo-polymer (100 mg/kg body weight) increased the swimming endurance capacity of mice by about 10 min and reduced the muscle and liver glycogen exhaustion by $18.5\%;and;67.2\%$, respectively. A substantial decrease in serum lactate accumulation ($50.7\%$) was also achieved under the influence of the exo-polymer. The exo-polymer was determined to be a glycoprotein with a molecular weight of 780 kDa and found to contain $82.8\%$ carbohydrate and $17.2\%$ protein.