Autologous stem cell transplantation (ASCT) is an effective treatment strategy for mantle-cell lymphoma (MCL) demonstrating significantly prolonged progression-free survival (PFS) when compared to interferon-α maintenance therapy of patients in first remission. The study of absolute lymphocyte count at day 15 (ALC-15) after ASCT as a prognostic factor in non-Hodgkin lymphoma (NHL) included different lymphoma subtypes. The relationship of ALC-15 after ASCT in MCL has not been specifically addressed. We evaluated the impact of ALC-15 recovery on survival of MCL patients undergoing ASCT. We studied 42 consecutive MCL patients who underwent ASCT at the Mayo Clinic in Rochester from 1993 to 2005. ALC-15 threshold was set at 500 cells/μl. The median follow-up after ASCT was 25 months (range, 2-106 months). The median overall survival (OS) and PFS times were significantly better for the 24 patients who achieved an ALC-15 ≥500 cells/μl compared with 18 patients with ALC-15 <500 cells/μl (not reached vs 30 months, P<0.01 and not reached vs 16 months, P<0.0006, respectively). Multivariate analysis demonstrated ALC-15 to be an independent prognostic factor for OS and PFS. The ALC-15 ≥500 cells/μl is associated with a significantly improved clinical outcome following ASCT in MCL.