The in vitro activity of cefodizime and two comparative cephalosporins, cefuroxime and ceftriaxone were studied against respiratory pathogens. MIC90s of cefodizime were 0.06-0.512 microgram/ml for Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae. MIC50s of cefodizime for Klebsiella pneumoniae and Staphylococcus aureus isolates were 2 micrograms/ml and 8 micrograms/ml respectively. Cefuroxime and ceftriaxone at a concentration of 2 micrograms/ml and 1 microgram/ml inhibited 50% of Klebsiella pneumoniae and 50% of Staphylococcus aureus strains studied respectively. Cefodizime inhibited many of the important respiratory pathogens and can be suggested as an active antimicrobial agent for respiratory tract infections.