Tumor-infiltrating lymphocytes, apoptosis, and angiogenesis have a pivotal role in tumor growth control. This study was undertaken to analyze the associations of these factors and their role in the prognosis, defined as survival time, of 56 patients operated on for small cell lung carcinoma (SCLC). Immunohistochemically detected T cells and macrophages were the most abundant tumor-infiltrating lymphocytes in SCLC, whereas the number of B cells was small. There was a trend in the number of intratumoral cytotoxic/suppressor CD8 cells that were associated with the extent of apoptotic bodies in SCLC, as measured by in situ 3′-end labeling of apoptotic DNA. A high number of intratumoral T cells and CD8 cells were associated significantly with a low tumor size (<3 cm)and low tumor stage (stages I–II). A high number of intratumoral macrophages were associated with a low tumor stage and angiogenesis, as measured by microvessel density. A high number of T cells, CD8 cells,and macrophages and a low tumor size (<3 cm) were prognostic markers predicting favorable survival time of the patients with SCLC.