© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. This study aimed to characterize the incidence, etiology and outcome of infectious episodes in patients with steroid refractory acute GvHD (SR-GvHD). The cohort included 127 adults treated with inolimomab (77%) or etanercept (23%) owing to acute 2-4 SR-GvHD, with a response rate of 43% on day +30 and a 4-year survival of 15%. The 1-year cumulative incidences of bacterial, CMV and invasive fungal infection were 74%, 65% and 14%, respectively. A high rate (37%) of enterococcal infections was observed. Twenty patients (15.7%) developed BK virus-hemorrhagic cystitis and five percent had an EBV reactivation with only one case of PTLD. One-third of long-term survivors developed pneumonia by a community respiratory virus and/or encapsulated bacteria, mostly associated with chronic GvHD. Infections were an important cause of non-relapse mortality, with a 4-year incidence of 46%. In multivariate analysis, use of rituximab in the 6 months before SCT (hazard ratio; HR 4.2; 95% confidence interval; CI 1.1-16.3), severe infection before SR-GvHD onset (HR 5.8; 95% CI 1.3-26.3) and a baseline C-reactive protein >15 UI/mL (HR 2.9; 95% CI 1.1-8.5) were associated with infection-related mortality. High rates of opportunistic infections with remarkable mortality warrant further efforts to optimize long-term outcomes after SR-GvHD.