Acute and chronic steroid-refractory graft-versus-host disease (srGVHD) is a life-threatening complication of allogeneic stem cell transplantation. There are a number of reports on case series describing efficacy of ruxolitinib in both acute and chronic srGVHD. We conducted a prospective study (NCT02997280) in 75 patients with srGVHD (32 acute, 43 chronic, 41 adults, and 34 children). Patients with chronic GVHD had severe disease in 83% of cases, and acute GVHD patients had grade III-IV disease in 66% of cases. The overall response rate (ORR) was 75% (95% CI 57-89%) in acute GVHD and 81% (95% CI 67-92%) in chronic. Overall survival was 59% (95% CI 49-74%) in acute group and 85% (95% CI 70-93%). The major risk factors for lower survival were grade III-IV gastrointestinal involvement (29% vs 93%, p = 0.0001) in acute form and high disease risk score in chronic (65% vs 90%, p = 0.038). Toxicity was predominantly hematologic with 79% and 44% of grade III-IV neutropenia in acute and chronic groups, respectively. There was no difference between adults and children in terms of ORR (p = 0.31, p = 0.35), survival (p = 0.44, p = 0.12) and toxicity (p > 0.93). The study demonstrated that ruxolitinib is an effective option in acute and chronic srGVHD and can be used both in adults and children.