The major value of prognostic markers in potentially curable non-small cell lung carcinoma (NSCLC) should be to guide therapy after surgical treatment. Although tumor-infiltrating T lymphocytes and plasma cells have been documented in NSCLC, a clear association with clinical outcome, especially for the stromal component, has not been well established. The aim of this study was to elucidate the prognostic significance of these cells/markers in the epithelial and stromal compartments of NSCLC. Tissue microarrays from 335 resected, stage I-IIIA, NSCLC were constructed by duplicate cores from viable neoplastic epithelial and stromal areas. Immunohistochemistry was used to evaluate the infiltration of CD3(+), CD117(+) as well as CD138(+) cells in epithelial and stromal areas. In univariate analyses, increasing numbers of stromal CD3(+) (p = 0.001) and epithelial CD3(+) cells (p = 0.004) correlated significantly with an improved disease-specific survival. No such relation was noted with CD3(+) or CD117(+) cells. In the multivariate analysis, stromal CD3(+) cells was an independent prognostic factor for disease-specific survival (HR 1.925, CI 1.21-3.04, p = 0.005). Increased presence of the pan T-cell marker, CD3, which is an independent factor, correlates with improved clinical outcome in NSCLC. This prognostic impact of T cells is clearer in the tumor stroma. Neither plasma cells nor mast cells were prognostic indicators in our cohort.