The prognostic value of immunophenotyping lymphomas with a panel of monoclonal antibodies (Mab) to various lymphoid antigens was assessed by studying 47 cases of diffuse large cell lymphoma. Cell suspensions were analysed by flow cytometry after labelling by indirect immunofluorescence. Thirty-eight cases were demonstrated to be of B cell and nine of T cell phenotype. Univariate analysis demonstrated that survival was significantly longer in patients expressing higher levels of HLA-DR (p = 0.01) and normal levels of CD8 (p = 0.04) but was not significantly associated with any of the other antigens. Our results support the possible value of HLA-DR in determining the prognosis of patients with diffuse large cell lymphoma.