We hypothesized that initial treatment of acute graft-versus-host disease (GVHD) with low-dose glucocorticoids (prednisone-equivalent dose of 1 mg/kg per day) instead of standard-dose glucocorticoids (prednisone-equivalent dose of 2 mg/kg per day) does not compromise major transplantation outcomes. We retrospectively analyzed outcomes among 733 patients who received transplants between 2000 and 2005 according to initial treatment with low-dose (n=347) versus standard-dose (n=386) systemic glucocorticoids. The mean cumulative prednisone-equivalent doses at day 100 after starting treatment were 44 and 87 mg/kg for patients given low-dose and standard-dose glucocorticoids, respectively. Adjusted outcomes between the groups given low-dose versus standard-dose glucocorticoids were not statistically significantly different: overall mortality (hazard ratio [HR], 1.10; 95% confidence interval [CI], 0.9-1.4), relapse (HR, 1.22; 95% CI, 0.9-1.7), nonrelapse mortality (HR, 1.06; 95% CI, 0.8-1.5). The small number of patients with grades III/IV acute GVHD at onset precluded definitive conclusions for this subgroup. In multivariate analysis, the risks of invasive fungal infections (HR, 0.59; 95% CI, 0.3-1.0) and the duration of hospitalization (odds ratio, 0.62; 95% CI, 0.4-0.9) were reduced in the low-dose prednisone group. We conclude that initial treatment with low-dose glucocorticoids for patients with grades I-II GVHD did not compromise disease control or mortality and was associated with decreased toxicity.