Cefprozil is a newer oral cephalosporin with a spectrum of activity against organisms that include gram-positive and gram-negative pathogens. A review of published data shows that cefprozil is active (susceptibility, less than or equal to 8 micrograms/mL; moderate susceptibility, 16 micrograms/mL; resistance, greater than or equal to 32 micrograms/mL) against gram-positive species such as streptococci, methicillin-susceptible staphylococci, and Listeria monocytogenes; it may have marginal activity against some enterococci. Among the gram-negative species, cefprozil has activity against Escherichia coli, Proteus mirabilis, Citrobacter diversus, Klebsiella pneumoniae, Klebsiella oxytoca, Haemophilus influenzae, and Moraxella catarrhalis. For anaerobic species, cefprozil has activity against clostridial species, including Clostridium difficile, peptostreptococci, and possibly Bacteroides melaninogenicus and Eubacterium. The activity of cefprozil is generally greater than that of cephalexin and generally similar to that of cefaclor. In these reports, cefprozil showed more in vitro activity than cephalexin and cefaclor against penicillin-resistant pneumococci, penicillin-resistant viridans streptococci, beta-lactamase-positive methicillin-susceptible Staphylococcus aureus, and C. difficile, although the clinical significance of some of these differences has yet to be studied.