This study included 44 children undergoing autologous marrow transplantation for leukemia between August 1979 and June 1987. Three of them received a second transplant. In the phase of neutropenia, 38 children presented with fever. Nineteen septicemia occurred (13 Gram positive cocci, 6 Gram negative bacteria), and 2 interstitial pneumonitis were observed. All children with documented infection or a fever of unknown origin recovered after treatment, except 3, who died from infection. The latest antimicrobial therapy used was a combination of an aminoglycoside and a third generation cephalosporin. When necessary, vancomycin or amphotericin B were added. After engraftment (granulocyte count greater than 0.5 X 10(9)/l) 14 septicemia (which recovered) and 10 herpes zoster infections were observed. Only one patient died of infection (herpes zoster with encephalitis).