Penetration of antibiotic preparations (gentamicin, neomycin, silver sulfadiazine, mupirocin) through Omiderm, a synthetic wound covering, was tested in vitro and in 5 patients with full-thickness burns who had undergone tangential excision and split-thickness skin grafting. All antibiotic preparations tested penetrated both meshed and unmeshed Omiderm. Omiderm did not affect the zones of inhibition of antimicrobial activity as compared with controls.