CLL remains incurable with the standard therapy. Allogeneic hematopoietic stem cell transplant may be curative. We examined 50 patients with advanced CLL who underwent allogeneic HCT at the University of Michigan between 1996 and 2006. Twenty-one patients received reduced-intensity conditioning (RIC) and twenty-nine patients received full-intensity conditioning (FIC) consisting of CY, etoposide and BCNU (n=20) or BU and CY (n=9). RIC recipients were older than FIC recipients (median age 54 vs 51, P=0.009). There were no statistically significant differences between groups in terms of the number of earlier therapies or patients with adverse cytogenetics. There were more unrelated donors in the RIC group 62% than in the FIC group 31% (P=0.030). Despite their older age and greater use of URD, the 5-year overall survival (OS) rate was 63% in the RIC group as compared with 18% in the FIC group (P=0.006). The primary cause of inferior survival in the FIC recipients was TRM, which was twice as high at day 100 for the FIC group 27% compared with the RIC group 14% (P=0.005). The relapse rate was 15% regardless with the majority of relapses occurring after day 100. These results suggest a favorable outcome for advanced CLL who undergo a RIC regimen compared with FIC.