The optimal treatment approach for patients with mantle cell lymphoma (MCL) is not well defined. Intensive therapeutic regimens result in high response rates and prolonged progression-free survival but at the expense of significant toxicity. We report here our results of the administration of rituximab plus chlorambucil (R-Chl) as first line treatment in patients with MCL. Twenty consecutively diagnosed patients were treated with this combination in which an induction and a maintenance arm were included. During induction, rituximab was administered at a dose of 375 mg/m(2) on day 1, while chlorambucil was given afterward at a dose of 10 mg/day for 10 consecutive days for eight cycles and then as a single agent for an additional four cycles. Maintenance consisted of rituximab administration every 2 months for 1 year. Most patients had indolent disease features such as a low mantle-cell international prognostic index (MIPI) score. The overall response rate was 95% (90% CR, 5% PR). Among patients in CR, 78% presented a molecular remission. The 3-year progression-free survival was 89%. There were no serious side effects. These results show that the R-Chl combination could be an effective therapeutic option as first line treatment in MCL, especially for patients with indolent disease characteristics.