We immunohistochemically examined 141 surgically resected peripheral lung adenocarcinomas for the expression of Fas, single stranded (ss-) DNA and Ki-67, and statistically evaluated the relationship of these parameters with other clinicopathologic variables, including clinical stage, nodal involvement, and histopathologic subtypes classified according to WHO criteria. Fas expression by cancer cells was characteristically localized in the cytoplasm, and the extent of expression correlated well with the degree of Ki-67 reactivity (p = 0.0004), but not with the degree of apoptic occurrence, as assessed by ss-DNA reactivity. Cancer cells of the bronchioloalveolar carcinoma (BAC) subtype without invasive growth exhibited a significantly lower Fas expression than those of other subtypes (p < 0.0001). Positive expression of Fas was frequently associated with a high incidence of nodal involvement and advanced clinical stage, as compared with cases of negative expression (p = 0.0111 and p = 0.0439, respectively). Multivariate analysis revealed that Fas expression significantly correlated with the histologic subtype, but not with tumor size, nodal involvement, or clinical stage. Survival analysis determined by the log-rank test revealed that clinical stage and Ki-67 reactivity were poor prognostic variables, and Fas expression was not statistically significant. Based on these data, intracytoplasmic expression of Fas in cancer cells may participate in the development of resistance to fas-mediated apoptosis.