We compared the in-vitro antibacterial activity of cefmetazole and other 4 antibiotics against clinical isolates. The minimal inhibitory concentration (MIC) of cefmetazole against 463 isolates was determined by standard (NCCLS) agar dilution testing, and compared with that of cefazolin, cefuroxime, cefotaxime and ceftazidime. The results showed that cefmetazole was the most effective in 5 antibiotics to indole (+)P. vulgaris and M. morganii (MIC(90) 8 mg/L), and cefmetazole had the same activity as cefotaxime (sensitive 82%-100%), but less activity than ceftazidime (sensitive 88%-100%) against E. coli, K. pneumoniae and P. morabilis. To oxacillin-sensitive staphylococci, cefmetazole was highly active, with the MIC 90 of 4 mg/L. Our results indicate that cefmetazole is highly active against Enterobacteriaceae and oxacillin-sensitive staphylococci.