Engraftment syndrome (ES) is an increasingly reported complication of hematopoietic stem cell transplantation (HSCT). In order to better characterize the clinical criteria for the diagnosis of ES, we retrospectively analyzed 125 autologous HSCT recipients. ES was first defined as the presence of noninfectious fever plus skin rash. Patients with and without these findings were compared (univariate and multivariate analyses) regarding the presence of weight gain, hypoalbuminemia, pulmonary infiltrates, diarrhea, neurological manifestations and jaundice. The variables that are significantly more frequent in patients with fever and skin rash were incorporated in the definition criteria. The final diagnostic criteria were noninfectious fever plus any of the following: skin rash, pulmonary infiltrates or diarrhea. The incidence of ES was 20%. The single risk factor for ES by multivariate analysis was a diagnosis other than Hodgkin's disease (odds ratio 6.17, 95% confidence interval 1.38-27.78). Patients with ES received empirical antifungal therapy more frequently than patients without the syndrome (40 vs 19%, P=0.03), and had a longer duration of hospitalization (P=0.0007). The prospective application of these diagnostic criteria may have a favorable impact on the early diagnosis of the syndrome, with the initiation of corticosteroids and a reduction in the unnecessary use of antimicrobial agents.