By transmission electron microscopy tumor infiltrating lymphocyte (TIL) in laryngeal squamous cell carcinoma tissues of 14 cases was studied. The results showed that the infiltrating lymphocyte in varying degrees eristed in laryngeal squamous cell carcinoma tissues. Most of them were present in a motionless state, and the others showed the feature of activated metrocyte and closely contracted with cancer cells and resulted in distinct morphological changes both the cancer cells and themselves. Therefore, this study provided an important morphological evidence for TIL as killer and inhibiter to the growth of cancer cells.