Cefoxitin is a new cephamycin antibiotic that has recently become available for clinical trial. We report here the results of an uncontrolled trial of cefoxitin treatment in 31 hospital patients with various acute infections, 20 of whom were cured. Serum, urine, and bile concentrations of cefoxitin greatly exceeded the minimum inhibitory concentration (MIC) required for clinically important Gram-negative organisms. We conclude that cefoxitin will have a place in the management of serious infections, particularly in the abdominal cavity and renal tracts.