The prognostic value of histochemical staining for HLA-DR was assessed retrospectively in 52 "curative" gastrectomy specimens from patients with gastric carcinoma. In addition other tumor variables, including histologic type, degree of differentiation, extent of local spread, prominence of mononuclear infiltrate, tumor edge, and lymph-node metastases, were examined. Sixty-five percent of the tumors showed positive staining for HLA-DR, and these tumors had a higher mean and median survival at 5 years compared with negative tumors. However, on multivariate analysis the difference was not statistically significant. The authors conclude that, although HLA-DR staining is associated with tumors of better prognosis, it cannot be used as an independent prognostic factor. Of the other tumor variables, only lymph-node status was of prognostic significance.