Of six new oral cephalosporins, cefixime and cefpodoxime were the most active (MIC for 90% of isolates tested [MIC90], 16 micrograms/ml) against Bordetella pertussis, followed by cefetamet, cefprozil, and loracarbef (LY163892) (MIC90, 64 micrograms/ml) and ceftibuten (MIC90, 128 micrograms/ml). Against Bordetella parapertussis, loracarbef was more active (MIC90, 32 micrograms/ml) than the other compounds tested (MIC90s, 64 to greater than 128 micrograms/ml). The new oral cephalosporins are unlikely to play a role in pertussis treatment.