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.