Allogeneic hematopoietic stem cell transplantation (allo-SCT) may offer a cure for selected patients with multiple myeloma (MM). Effective prognostic markers to guide patient selection are warranted. We retrospectively studied a cohort of 100 relapsed refractory MM patients who underwent allo-SCT. With a median follow-up of 12.2 years, median overall survival (OS) and progression-free survival (LFS) were 9.2 months and 5.6 months, respectively. 5-years OS and PFS were was 18.0% and 16.8%. The cumulative incidence of 5-years relapse was 45.9% and non-relapse mortality (NRM) 36.0%. In a multivariable Cox model, decreasing albumin, increasing lactate dehydrogenase (LDH), advanced disease, and mismatched donors were predictive of both reduced OS and PFS. The probability of 5-years OS was higher in patients with LDH below vs. the upper limit of normal (22% vs. 5%, p = 0.004). In the multivariable analysis, the hazard of NRM was increased with low albumin, mismatched donor type, and declining estimated glomerular filtration rate (eGFR). Patients with a low eGFR had a 5-year NRM incidence of 31% vs. 56% in patients with higher levels (p = 0.02). Graft-versus-host disease was not associated with improved outcomes. In conclusion, LDH, renal function, and albumin are highly informative of outcomes in MM patients treated with allo-SCT.