Hericium erinaceus is a Chinese herbal medicine. The Apollo oral liquid contains polysaccharide of H. erinaceus (PHE). The effects of PHE on proliferation of mice T and B lymphocytes were studied. Results showed that (1) 3-fold proliferation of thymocytes was demonstrated when PHE were administrated with Con A than Con A alone. Such effect on thymocyte was not observed when PHE was used alone. (2) Proliferation of spleen lymphocytes was also stimulated when PHE were taken together with lipopolysaccharide, which was 50% and 3 times stronger than that of using lipopolysaccharide and PHE alone respectively.