Twelve beta-lactams (11 cephalosporins and aztreonam) were compared in an infant rat model of Haemophilus influenzae, type b meningitis. Ceftazidime was the most effective compound tested and showed greater activity than cefuroxime, latamoxef (moxalactam) and cefotaxime--all of which have been used successfully in clinical haemophilus meningitis in children.