SummaryWithin a 7-year period 1, 597 newly diagnosed cases of non-Hodgkin's lymphoma (NHL) were included in a Danish population-based NHL registry. Of these, 602 (38%) were aged 70 years or older (age range 70–94, median: 76.8). They represent the population defined as ‘elderly’ patients in the present study. The average annual incidence rate for this elderly patient population was 35.7/10⁵, as compared with 6.6/10⁵ for patients aged <70 (overall annual incidence: 9.5/ 10⁵). Localised cases (stage I and II) and extranodal manifestations were found more frequently among elderly patients. The most common sites of extranodal involvement were the stomach (21% of all extranodal cases) and the bone marrow (16%). Histologically, follicular centroblastic/centro-cytic cases were found to be less frequent (p < 0.01) in elderly patients as compared to their younger counterparts (<70 years), who in contrast had a lower occurrence of diffuse centroblastic cases (p < 0.01). Over all 7-year survival for the elderly patient population was 35% (median 1.7 years), and for patients aged <70 it was 57%. This difference persisted after correction for apparently NHL-unrelated deaths (52% vs. 66%, respectively, p < 0.0001). Elderly patients with poor prognosis were characterised by the following features identified in a Cox-regression model: hepatic involvement, presence of B-symptoms, high-grade histology and elevated s-LDH. The corresponding relative risk values were in the order 2.4, 2.2, 1.9 and 1.6.