A topical infection model for the study of the effectiveness of antimicrobials was developed. Animals were laparotomized, sutured with braided silk, and inoculated with a strain of
Staphylococcus aureus
. The test organism was phage typed, and its antibiotic spectrum was determined. Concentrations of bacteria from 5 × 10
4
to 10
8
cells per incision produced large body wall stitch abscesses with occasional drainage through the skin. This laparotomy infection is readily reproducible and can be used for evaluation of the ability of topical antimicrobials to prevent
S. aureus
stitch abscesses.