The in vitro activity of biapenem, a new carbapenem, against 535 clinical recent isolates was compared with those of other antibiotics. Biapenem showed broad-spectrum activity against gram-negative and gram-positive clinical isolates. The new carbapenem was more active than imipenem against members of the family Enterobacteriaceae with MIC90S ranging from 0.12 to 2 mg/l and from 0.25 to 4 mg/l, respectively. Moreover it was 2-fold more active than imipenem against Pseudomonas aeruginosa (MIC90, 8 and 16 mg/l, respectively). Taken together, these results indicate that biapenem shares the favorable in vitro activity properties of imipenem and merits further study in the treatment of infections caused by a wide range of pathogens.