Biapenem (L-627) was evaluated for its efficacy and safety. The following results were obtained. L-627 was given to 9 patients with infections: 3 with pneumonia, 1 with acute bronchopneumonia, 1 with acute bronchitis, 1 with bacteremia, 1 with tonsillitis, 2 with exceptional case. Therapeutic responses were excellent in 3, good in 4, with an efficacy rate of 100%. Adverse reactions were noted. No abnormalities were shown in laboratory data. It has been concluded that L-627 is a useful drug for the treatment of bacterial infections in children.