We report the outcome following RIT for NHL in 88 patients (LG-NHL n = 41, HG-NHL n = 37, MCL n = 10). Thirty-seven had received prior autografts and 21 were in CR at transplant. Conditioning was with alemtuzumab, fludarabine and melphalan. Sixty-five patients received PBSC from HLA-identical siblings and 23 received BM from matched unrelated donors. GVHD prophylaxis was with cyclosporin A. Grade III-IV acute GVHD developed in 4 patients and chronic GVHD in 6 patients. With a median follow-up of 36 months (range 18-60), the actuarial overall survival (OS) at 3 years was 34% for HG-NHL, 60% for MCL and 73% for LG-NHL (p < or = 0.001). The 100-day and 3-year TRM for patients with LG-NHL were 2% and 11%, respectively, and were better (p = 0.01) than for patients with HG-NHL (27% and 38%, respectively). The actuarial current progression free survival (PFS) at 3 years, including those who achieved remission following DLI for progression, was 65% for LG-NHL 50% for MCL and 34% for HG-NHL (p = 0.002). Twenty-one patients received DLI for MRD, persistent disease or relapse and 15 received DLI for mixed hematopoietic chimerism. Patients with relapsed LG-NHL and CLL achieve excellent PFS with extremely low TRM and GVHD, even when matched family donors are unavailable.