Background: Combined modality treatment consisting of chemotherapy (CT) followed by involved field radiotherapy (IF-RT) is the standard treatment for early unfavourable Hodgkin’s lymphoma (HL). Despite high complete remission (CR) rates, failures are common. We thus compared the baseline-dose BEACOPP regimen with ABVD and 20 with 30 Gy IF-RT in a prospectively randomized trial (HD11) in an attempt to improve outcome in this group of patients. Methods: Between May 1998 and January 2003, 1570 patients (pts) aged 16–75 with untreated intermediate stage HL (CS I, IIA with risk factors or IIB with elevated ESR and/or ≥3 nodal areas only) were randomized according to a factorial design between 4 cycles of ABVD followed by 30 Gy IF-RT (arm A - standard treatment), 4 ABVD + 20 Gy IF-RT (arm B), 4 baseline-dose BEACOPP + 30 Gy IF-RT (arm C) and 4 baseline-dose BEACOPP + 20 Gy IF-RT (arm D). Results: In the fifth preplaned interim analysis, 1293 pts were evaluable for the chemotherapy comparison and 1274 for the radiotherapy comparison. Patient characteristics were well balanced between the treatment arms. 95% of patients treated reached CR, 2% had pogressive disease, 8% relapsed and the total mortality rate was 4% with no significant differences between treatment arms for either endpoint. The most frequent haematological toxicities during chemotherapy were leucopenia observed in 32% of pts (ABVD: 25%, BEACOPP: 39%) and anemia in 4% of pts (ABVD After a median observation time of three years, freedom from treatment failure (FFTF) was 87% (95%-CI 85–89) and overall survival (OS) was 96% (95%-CI 95–97). Both for FFTF and OS, there was no sequential significant difference either between ABVD (FFTF 87%, OS 97%) and BEACOPP (FFTF 88%, OS 96%) nor 30 Gy (FFTF 90%, OS 97%) and 20 Gy IF-RT (FFTF 87%, OS 97%). Conclusions: At three years of median observation time, no sequential significant differences in treatment outcome were detected, neither between chemotherapy regimens nor between the different doses of radiotherapy, despite more relapses in 20 Gy radiotherapy arms.