Whether high-dose therapy (HDT) plus autologous stem cell transplantation (ASCT) ought to be included in the initial treatment plan for those patients with unfavourable Hodgkin's disease, a wide cooperative study (HD01 protocol) was approved, comparing HDT followed by ASCT vs conventional chemotherapy (CT). Patients were eligible for the study if they had at least two of the following adverse prognostic factors: high serum LDH levels, mediastinal mass >0.45, more than one extranodal involved site, low hematocrit (<34% for women and <38% for men), and inguinal involvement. Those patients achieving complete or partial remission with four courses of ABVD or ABVD-containing chemotherapy were randomized to receive either HDT plus ASCT or four additional courses of chemotherapy, followed by ASCT in second remission, if appropriate. Between April 1993 and September 1995, 55 patients from 14 different centers have been enrolled into the trial. Twenty patients (45%) were in stage IV, and 37 patients (84%) had systemic symptoms. Twenty-seven patients (61%) had two adverse prognostic factors, and 17 patients (39%) had three or more risk factors. After four cycles of ABVD-containing CT, 44 patients were assessable for response. Overall 12 patients achieved CR (27%), 25 obtained a PR (57%) and seven patients failed to respond (16%). Thirty-six patients were randomized between ASCT (20 patients) or four additional cycles of conventional CT (16 patients). With a median follow-up after ASCT of 13 months (range 1-23 months), no major ASCT-related toxicity has been reported to the trial office. In conclusion, the first 44 patients registered in the HD01 trial and assessable for response, had a very aggressive disease and responded poorly to conventional CT, thus warranting a more aggressive approach, such as HDT followed by ASCT.