A prospective, randomized, controlled multicenter trial was performed to evaluate the efficacy and safety of once-daily oral monotherapy with 500 mg levofloxacin in comparison with 4.5 g piperacillin/tazobactam 3 times a day in patients with low-risk febrile neutropenia. Low risk was defined by oral temperature > or = 38.5 degrees C on one occasion or > or = 38.0 degrees C twice within 24 hours and granulocytopenia < or = 500/microL for less than 10 days. The primary end point was defined as defervescence after 72 hours followed by at least 7 afebrile days. Secondary end points were overall response, time to defervescence, survival on day 30, and toxicity. Thirty-four episodes were included. Fever of unknown origin accounted for 26 (76.5%) of the episodes, microbiologically defined infection for 5 (14.7%) of the episodes, and clinically defined infection for 3 (8.8%) of the episodes. On an intent-to-treat basis, all episodes were evaluable for the primary end point. Levofloxacin and piperacillin/tazobactam were successful after 72 hours of treatment in 76.5% and 88.3% of the episodes. Overall response was achieved in 94.1% and 100% of the episodes, respectively. One inpatient in the oral treatment group died of septic shock without identification of a causative pathogen. A larger phase III trial is warranted to further evaluate the lack of inferiority of the oral monotherapy regimen versus standard intravenous therapy.