Donor lymphocyte infusion (DLI) is an option for relapsed hematologic malignancies or incomplete chimerism of non-malignant diseases following allogeneic hematopoietic cell transplantation (HCT). We analyzed the incidence of acute GvHD (aGvHD) in patients treated with DLI. From 1995 to 2013, 171 DLIs were given to 120 patients. The cumulative incidence of post-DLI grade II-IV aGvHD was 33% (CI 25-42%, n=40; 12 grade II), and of grade III-IV 24% (CI 16-32%, n=28). GvHD after DLI (n=46) involved the skin in 70% (n=32), lower gastrointestinal (GI) 65% (n=30), upper GI 43% (n=20) and liver 35% (n=16). Patients receiving chemotherapy accompanying the DLI (chemo-DLI) (n=37) had more frequent aGvHD and particularly lower GI GvHD. Risk factors for grade II-IV aGvHD included age >40, chemo-DLI, malignant disease and time from HCT to DLI <200 days. aGvHD response to treatment at 8 weeks was complete in 40% and complete/partial (CR/PR) in 52%. Chemo-DLI had higher response rates to aGVHD treatment in non-CML malignancies. We observed frequent, yet therapy-responsive aGvHD following DLI. GI GvHD in particular is a significant risk when giving chemotherapy prior to DLI. Improvements in DLI efficacy and GvHD management are still needed.