Efficacy and safety of sulbactam/cefoperazone (SBT/CPZ) was studied on gynecological infections. The results obtained are as follows: In the treatment of 31 cases of gynecological infections, the clinical efficacy of SBT/CPZ was assessed as excellent in 9 cases and effective in 22 cases. As for the bacteriological effects of SBT/CPZ, clinically isolated organisms were completely (100%) eradicated. In comparison with MICs of CPZ, SBT/CPZ was found to show a combined effect on Gram-negative and Gram-positive organisms in the order mentioned, but this effect was not observed against anaerobes. The combined effect of SBT/CPZ on beta-lactamase producing bacteria was also investigated in the same manner. As a result, SBT/CPZ was found to exert a combined effect on beta-lactamase strains of S. aureus, S. epidermidis, E. coli, B. catarrhalis and B. fragilis. The laboratory tests performed before and after administration of SBT/CPZ revealed rise in GOT and GPT values in 1 case, GPT values in 2 cases and eosinophil in 1 case. However, these rises were all mild and required no particular measures.