The results of in vitro and in vivo studies of cefmetazole, a second-generation cephamycin, were reviewed. Cefmetazole's spectrum of activity includes clinical coverage of many Enterobacteriaceae, staphylococci, streptococci, Haemophilus species, pathogenic Neisseria organisms, Moraxella (Branhamella) catarrhalis and anaerobic bacteria. Cefmetazole is generally two to eight times more potent than cefoxitin against organisms within their spectra and is most active against staphylococci (minimal inhibitory concentration90 = 2.0 micrograms/mL). Methicillin-resistant Staphylococcus aureus strains are more susceptible to cefmetazole, alone or in combination with fosfomycin, than to any other cephamycins, and cefmetazole is remarkably resistant to the beta-lactamases produced by aerobic and anaerobic bacteria. The incidence of adverse drug reactions is low (8.8% in the United States, 2.2% in Japan), and the drug has been demonstrated to have cost-containment potential.