The proliferation of splenocytes from healthy adults was induced by anti-CD3 McAb, PHA and IL-2. The proliferative capability and anti-tumor activity as well as phenotypes of the splenocytes cultured in different medium systems were studied. The results showed that anti-CD3 McAb and PHA not only enhanced the proliferation of splenocytes induced by IL-2, but also produced synergism if used simultaneously. The expressions of CD4 and Tac of cellular surface markers were increased after splenocytes were induced by anti-CD3 McAb and PHA. The results of anti-tumor activity of LAK cells suggested that PHA had the capability to promote anti-tumor activity of LAK cells by both direct and indirect pathways, but anti-CD3 McAb indirectly promoted anti-tumor activity of LAK cells by enhancing splenocyte proliferation.