Engraftment syndrome (ES) following autologous hematopoietic stem cell transplantation (AHSCT) is characterized by fever and rash. In January 2002, we instituted steroid prophylaxis for ES from day +4 to +14. This study was conducted to assess whether this practice increased the risk of infection. In total, 194 consecutive patients were reviewed, 111 did not receive steroid prophylaxis (group A), and 83 did (group B). Initial antimicrobial prophylaxis was the same in both groups. There were no significant differences between groups in age, gender, race, prior radiation therapy, number of prior chemotherapy regimens, disease status at transplant, mobilization regimen, days of leukopheresis, CD34(+) cell dose, and days to platelet and neutrophil engraftment. Group B had significantly fewer patients with non-Hodgkin's lymphoma and multiple myeloma, shorter median duration from diagnosis to transplant, lower risk of ES, and shorter mean length of hospital stay. The incidence of early and late microbiologically confirmed infections was not significantly different between groups. Types of infections and types of organisms identified were similar in both groups. Hospital readmission rates were similar in both groups. Steroid prophylaxis significantly decreases the risk of ES following AHSCT, and is associated with shortened hospitalization, without increasing risk of infection.