Thirty evaluable patients with acute leukemia (AL), aged 14 to 48-year-old received remission induction chemotherapy on a protected environment-prophylactic antibiotic program. Twenty-seven (90%) of these patients achieved complete remission and 17 remained in complete remission for 1 to 22 months. Although these patients spent 36% of their time with neutrophil counts less than 100/mm3, they spent only 20% of their time with fever. Major infection was present during only 7% of the days when neutrophil count was less than 100/mm3. No patient died of an infectious complication during remission induction therapy.