Immunophenotyping shows heterogeneity of expression of activation and differentiation antigens in B-cell non-Hodgkin's lymphoma (NHL). To investigate whether antigen expression correlates with clinical behaviour we have studied the clinical presentation and follow-up of a series of 111 B-cell lymphomas previously phenotyped for a panel of antigens including CD groups 5, 9, 10, 21, 23, 25, 30, 38, 4F2 antigen, and transferrin receptor. CD antigens 5, 10, and 23 were expressed significantly more often by low grade lymphomas whereas CD38, 4F2 antigen, and transferrin receptor were more often expressed by high grade lymphomas. There was a significant correlation with survival and age, stage at presentation, histological grade, and expression of 4F2 antigen and transferrin receptor but not with the other antigens studied. 4F2 antigen and transferrin receptor may identify a poor prognostic group of cases in low grade lymphoma but we conclude that phenotyping B-cell NHL for many of the antigens expressed at various stages of B-cell differentiation and activation does not provide clinically useful information in addition to that obtained from standard histological classifications.