Pexiganan, an antimicrobial peptide, is a synthetic analog of the magainin II peptides originally isolated from the skin of the African clawed frog. In this study, pexiganan was shown to have broad-spectrum antimicrobial activity when it was tested against 580 clinical isolates of Gram-positive and Gram-negative aerobic bacteria by broth microdilution method as recommended by NCCLS. The MIC₉₀ values of pexiganan were detected as 32 µg/ml for Escherichia coli Klebsiella spp., Enterobacter spp. and 64 µg/ml for Pseudomonas aeruginosa The MIC₉₀ values of pexiganan for Staphylococcus aureus, coagulase-negative staphylococci, and Enterococcus faecium were 16 µg/ml. Enterococcus faecalis and Proteus spp. were found to be less susceptible to pexiganan with both MIC₅₀ and MIC₉₀ values greater than 256 µg/m These results demostrate that pexiganan could serve as a potent topical antimicrobial substance.