In the current study, we evaluated a combination of tacrolimus and mycophenolate mofetil (MMF) as GvHD prophylaxis in 50 patients undergoing truly nonmyeloablative (NM; 90 mg/m(2) fludarabine, 2 Gy TBI) hematopoietic SCT (HSCT) from unrelated donors. Median patient age was 51 years (range, 25-67 years). After a median follow-up of 1123 days (range, 47-2729 days), 20 patients (40%) are alive and free from disease. The probabilities of 1-, 2- and 3-year survival were 57, 47 and 39%, respectively. Patients who achieved a remission before HSCT had a significantly better OS compared with those who had active disease (P=0.01). The incidences of grade II-IV and III-IV acute GvHD (aGvHD) were 54% (n=27) and 16% (n=8). Remarkably, using tacrolimus and MMF, the median onset of aGvHD occurred distinctly late on day +66 (range, 12-119 days). A total of 46 patients were evaluable for chronic GvHD (cGvHD). Out of these, 26 (56%) patients developed cGvHD, with 16 (34%) of them showing limited and 10 (21%) showing extensive disease. We conclude that the combination of tacrolimus and MMF as post transplant immunosuppression for patients receiving NM unrelated donor HSCT permits stable engraftment and effective prophylaxis for acute and cGvHD. In particular, the occurrence of severe early-onset aGvHD was attenuated.