Background: Outcomes of pts with APL have dramatically improved, especially with availability of all-trans retinoic acid (ATRA), arsenic trioxide, and better supportive care. However, a small but significant number of pts relapse despite optimal upfront therapy. Methods: We reviewed pts with APL treated at our institution (1980-2010). Outcome of pts who received autologous (auto) or allogeneic (allo) HCT for relapsed disease was compared with those who did not. Results: We identified 42 pts with relapsed/refractory APL. 25 (60%) pts received auto (8) or allo HCT (17: related 5, unrelated 12). Median (med) age of pts receiving HCT: 29 years (range 6-61). RT-PCR was negative for PML/RARα at time of HCT in 6 of 6 evaluable auto pts and in 6 of 8 evaluable allo pts. Of the 8 auto pts, 5 were in CR2 and 3 in ≥ CR3. Preparative (prep) regimen: Busulfan (Bu) + Cyclophosphamide (CY) in 7 pts and Bu + Fludarabine (Flu) in 1 pt. Of the 17 allo pts, 12 were in CR2 and 5 in ≥CR3. Prep regimens for allo HCT: Bu + Cy 7, TBI-based 4, Bu + Flu 4, Flu + Melphalan 2. Successful engraftment: 24 (96%) HCT pts; only 1 pt (auto) died of graft failure after 2.7 months. Grade 2-4 acute GVHD: 6/17 pts (35%); limited or extensive chronic GVHD in 10/17 pts (59%). Med follow up (f/u): 82 months. Transplant-related mortality after auto or allo HCT: 37% and 41%, respectively. 7-year progression-free survival (PFS) after auto and allo HCT: 50% and 33% (p=0.66), respectively. 7-year overall survival (OS) after auto and allo HCT: 50% and 41% (p=0.65), respectively. At last f/u, 11/25 (44%) were alive, with 9/25 (36%) pts alive and in remission, between 2 to 19 years post HCT. Most common causes of death (COD): relapse 4, GVHD 5, infection 2. In the 17 pts who did not undergo HCT, med age was 45, pts received a med of 2 lines of therapy with 7 pts receiving ≥3 lines of therapy. APL relapse was most common COD (6 of 9 pts who died). 7-year OS from diagnosis: 40%, in contrast to 45% in pts receiving auto or allo HCT (p=0.48). Conclusions: In this retrospective study, both auto and allo HCT are associated with durable remission and prolonged survival. OS was not significantly different from pts who did not receive HCT.