The antibacterial activity of a new parenteral cephalosporin, FK037 was assessed against recent aerobic and anaerobic strains isolated from patients in the fields of obstetrics and gynecology during the period between January 1992 and June 1993. The MICs of FK037 for 90% of the clinical isolates tested were 0.10 microgram/ml for Escherichia coli and Klebsiella pneumoniae, 0.20 microgram/ml for Streptococcus agalactiae, 0.39 microgram/ml for Gardnerella vaginalis, 0.78 microgram/ml for Staphylococcus epidermidis, Peptostreptococcus anaerobius and Mobiluncus spp., 1.56 micrograms/ml for Peptostreptococcus magnus, 3.13 micrograms/ml for methicillin-sensitive Staphylococcus aureus, 25 micrograms/ml for methicillin-resistant S. aureus (MRSA), Bacteroides fragilis and Prevotella disiens, 100 micrograms/ml for Bacteroides thetaiotaomicron and Prevotella bivia; and > 100 micrograms/ml for Enterococcus faecalis. FK037 was superior in potency to ceftazidime against all strains except E. faecalis, P. anaerobius and P. bivia. It was 4- to 16-fold more active than cefotaxime against aerobic gram-positive bacteria and P. disiens, and its activity was similar to that of cefotaxime against the other strains. FK037 had 4- to 16-fold stronger activity than flomoxef against MRSA, S. agalactiae and E. coli and a similar activity to flomoxef against the other strains except G. vaginalis and B. fragilis that were 4-fold more sensitive to flomoxef than to FK037.