Fifteen patients with bone joint infections were treated with 1.0 g of cefonicid administered intravenously or intramuscularly once daily. Single organisms isolated included Staphylococcus aureus (from six patients), Staphylococcus epidermidis (three), and Peptococcus species (one). For four patients infection was polymicrobial, and for one patient no organism was isolated. The mean duration of therapy was 40.4 days, only 10.9 days of which were spent in the hospital. The remainder of therapy was administered intramuscularly in an ambulatory setting. Therapy was successful in all 12 assessable patients. No clinical or bacteriologic relapse occurred in the follow-up period of three to 13 months. The occurrence of adverse effects prompted discontinuation of cefonicid therapy in three patients. Minimum savings in hospital-bed costs alone were $64,350, with 390 hospital days avoided. The minimum savings in work income were $10,010, with 182 days of absenteeism avoided. These data are preliminary but suggest efficacy of cefonicid in a mode of therapy that could have profound cost benefits.