Cefadroxil is a semisynthetic cephalosporin with a broad spectrum of activity. It is chemically stable, acid resistant, and well absorbed after oral administration. The bactericidal activity of cefadroxil as compared with that of cephalexin was determined against the following bacterial species: E. coli, Klebsiella pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae. Against Staphylococcus aureus and Streptococcus pneumoniae cefadroxil showed more activity than cefalexin, whereas they showed similar activity against Streptococcus pyogenes. Cefadroxil showed more bactericidal activity than cefalexin against Gram-negative strains.