An animal model was developed to study whether Staphylococcus aureus could penetrate a sutured wound. Six days after bacteria were applied to sutured incisions, viable organisms could be recovered from the depths of the wounds in the majority of cases. Specifically, bacteria could be recovered in 23 of 24 wounds when they were applied 1 day after suturing, in 17 of 24 wounds when they were applied 4 days after suturing, and in 13 of 24 when applied 7 days after suturing. When Steri-strips were used to close the wounds, bacteria could not be recovered from any of 24 wounds when bacteria were applied 4 or 7 days after wound closure. When bacteria were applied 5 min after sutures had been placed but without incision, bacteria could be recovered in three of 12 cases and in two of 12 cases when they were applied 7 days after suturing. These results demonstrate that bacteria can penetrate sutured wounds. The sutures themselves probably contributed to this phenomenon.