Objective: To investigate the in vitro efficiency of two kinds of polylatic acid (PLA) immunomicrospheres: M1(hAFP158~166)and M2(hAFP218~226) in specific inducement of CTL and the cytotoxicity of CTL against hepatocellular carcinoma cells. Methods: Pripheral blood monocytes (PBMC) of HLA-A2+ healthy volunteers stimulated in vitro by peptide-loading microspheres were taken as effectors. The experiments were divided into three groups: control group, hAFP+ tumor cells group, and hAFP- tumor cells group. The specific cytolysis of target cells was assessed by 51Cr-release assay. Results: Both M1 and M2 induced proliferation of HLA-A2+ PBMC, forming visible clones. The effector cells induced by M1 and M2 both had an cytolysis rate over 75% for hAFP+ tumor cells, which was significantly higher than that for hAFP- tumor cells (P0.05). Conclusion: The two kinds of microspheres can both induce specific CTL in vitro, which can effectively kill hAFP+ tumor cells.