We analysed the impact of age and gender on biology and outcome of 2084 patients diagnosed with non-Hodgkin lymphoma (NHL) between October 1986 and December 2002 and treated according to the Berlin-Frankfurt-Münster (BFM) multicentre protocols NHL-BFM-86, -90 and -95. Median age at diagnosis was 8.0 years for 97 precursor B-lymphoblastic lymphoma (pB-LBL) patients, 8.8 years for 335 T-lymphoblastic lymphoma (T-LBL) patients, 8.4 years for 1004 Burkitt's lymphoma/leukaemia (BL/B-AL) patients, 11.4 years for 173 diffuse large B-cell lymphoma (centroblastic subtype) (DLBCL-CB) patients, 13.2 years for 40 primary mediastinal large B-cell lymphoma (PMLBL) patients and 10.8 years for 215 anaplastic large-cell lymphoma (ALCL) patients (P < 0.00001). The male:female ratio was 0.9:1 for pB-LBL and PMLBL, 1.7:1 for DLBCL-CB, 1.8:1 for ALCL, 2.5:1 for T-LBL and 4.5:1 for BL/B-AL (P < 0.00001). The probability of event-free survival at 5 years (5-year pEFS) was 85 +/- 1% for all 2084 patients [median follow-up 5.7 (0.1-15.9) years], and was significantly superior for male T-LBL and DLBCL-CB patients. Comparing age-groups 0-4, 5-9, 10-14 and 15-18 years, pEFS was inferior for the youngest patients only in the pB-LBL- and ALCL-groups. T-LBL and DLBCL-CB adolescent females had worse outcome than younger girls while age had no impact on pEFS for boys. We conclude that the distribution of age and gender differed between NHL-subtypes. The impact of gender on outcome differed between NHL subgroups. The prognostic impact of age differed not only by NHL-subtype but also according to gender in some subtypes.