The in-vitro activity of cefpirome, a new injectable cephalosporin, was compared with that of several other antibiotics against bacterial isolates from hospitalized patients with lower respiratory tract infections, urinary tract infections and wound infections. Minimum inhibitory concentrations were determined for 874 strains against 16 antibiotics using a microtitration technique. Cefpirome showed a very broad spectrum of activity against most pathogens tested. The spectrum included organisms such as Staphylococcus spp., enterococci, Enterobacter spp., and Pseudomonas spp. which are frequently resistant to third generation cephalosporins.