E1101 is a new oral cephalosporin with a broad spectrum of antibacterial activity. It inhibited more than 90% of clinical isolates of Streptococcus agalactiae, Escherichia coli and Peptostreptococcus magnus at the concentration of 3.13 mg/l. E1101 was the most active agent against S. agalactiae and E. coli. Since none of the compounds was sufficiently active against the Bacteroides fragilis and Prevotella bivia isolates, they are not appropriate in the treatment of patients with infections caused by these organisms. The results of this study suggest that, subject to confirmation by clinical trials, E1101, in combination with an agent with reliable activity against anaerobic bacteria, is suitable as empirical therapy of patients with obstetric and gynecological infections.