In order to examine whether or not the expression of the apoptosis-related receptor Fas (CD-95/APO-1) and its ligand (FasL) has relevance for patient survival, immunohistochemistry was used to analyze the proteins of both factors in 164 non-small cell lung carcinomas. Patients with Fas-positive tumors exhibited significantly longer survival times than patients with Fas-negative carcinomas. In contrast, FasL did not significantly influence patient survival time. A multivariate analysis of clinical and biological factors indicated that lymph node status and Fas expression were significant prognostic factors. Carcinoma patients who were negative for both Fas and FasL had a significantly higher incidence of lymph node involvement than did carcinoma patients who were positive for Fas and FasL. Carcinomas that were positive for Fas and FasL demonstrated a greater sensitivity to doxorubicin in vitro.