This report describes the long-term outcome of a cohort of 127 de novo multiple myeloma patients treated with at least one course of high-dose therapy (HDT) in a single institution between June 1985 and December 1995, for whom the minimum follow-up duration for survivors is 6 years. The 12-year overall survival (OS) and event-free survival (EFS) rates are 24.9% and 3.1%, respectively, and the median survival and EFS are 49 and 17 months, respectively. Only four patients are alive and disease-free 79, 90, 132 and 153 after the first HDT, respectively. Three of them received a subsequent allogeneic bone marrow transplantation. Three factors significantly influence OS in this series: B2M at diagnosis, age, and the completion of a second HDT. The 10-year survival is 18.9% for the group of patients with B2M level >3 mg/l at diagnosis as compared with 41% for patients with B2M < or =3, with a median survival of 31 months vs 73 (P = 0.01). The 10-year survival is 23.4% for the group of patients aged >55 years as compared with 36.5% for patients aged <55 years, with a median survival of 34.5 months vs 70.5 (P = 0.04). The 10-year survival is 20.4% for the group of patients who did not receive a second HDT as compared with 35.2% for patients who completed a second HDT, with a median survival of 29 months vs 70 (P = 0.02). In this study we show that some patients treated with HDT experience durable remission and prolonged survival. This survival is significantly influenced by age (< or =55 years), B2M at diagnosis (< or =3 mg/l) and by the completion of two cycles of HDT.