Antibiotic therapy in granulocytopenic cancer patients, the risk factors predisposing these patients to infection, and the signs, symptoms and types of infections occurring in these patients are reviewed. The four most commonly isolated organism at most cancer treatment centers are Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa and Staphylococcus aureus. Early antimicrobial therapy with broad-spectrum antibiotics before culture results are known produces cure rates of approximately 70%, regardless of the combination used. The most important predictor of response to any antibacterial regimen is a rise in the absolute granulocyte count. The current recommended fever regimen would be carbenicillin (or ticarcillin) with an aminoglycoside. The choice of an aminoglycoside depends on the prevailing organism sensitivities at a particular institution; in many cases, gentamicin sulfate is suitable. Addition of a cephalosporin to the two-drug regimen offers little increase in cure rates, except whem aminoglycoside-resistant Enterobacteriaceae are prevalent. Because of nephrotoxicity produced with combinations of cephalothin sodium and the aminoglycosides, cefazolin sodium would be the current cephalosporin of choice. An alternate third drug to be considered is co-trimoxazole, a broad-spectrum antimicrobial not yet commercially available in parenteral form. In the absence of a clinical response to appropriate antimicrobial therapy in documented infections, granulocyte transfusions may be indicated.