Mantle cell lymphoma (MCL) is rarely cured with standard-dose chemotherapy. From January 1997 to February 2000, 28 previously untreated advanced-stage MCL patients younger than 61 years of age were treated at 9 Italian hematologic departments with 3 cycles of standard-dose debulking chemotherapy followed by a high-dose rituximab-supplemented sequence (R-HDS) including intravenous administration of high-dose cyclophosphamide, high-dose cytarabine, high-dose melphalan, and high-dose mitoxantrone plus melphalan. Study end points included toxicity, clinical and molecular response rates, long-term event-free survival (EFS), and overall survival (OS) rates, as well as the ability to harvest tumor-free peripheral blood stem cells. Optimal amounts of polymerase chain reaction-negative (PCR-negative) CD34+ cells were collected from all 20 informative patients. One patient died of toxicity. All 27 patients assessable for response achieved a complete response (CR), of which 24 remain in continuous complete remission (CCR) after a median follow-up of 35 months. Three patients had transient evidence of PCR-detectable disease in the bone marrow. The OS and EFS rates at 54 months were 89% and 79%, respectively. These results compare with the 42% OS rate and the 18% EFS rate observed in 35 age-matched historic controls treated with standard-dose chemotherapy at the participating centers. The use of rituximab in combination with high-dose chemotherapy represents a very effective in vivo purging method. The R-HDS regimen can be safely applied in a multicenter hematology setting and leads to long-term EFS and OS in the majority of patients with an otherwise incurable disease.