To evaluate the effect of a thin, transparent, adhesive and elastic polyurethane drape permeable only to gas and water vapor molecules but not to bacteria in comparison to a conventional drape for postoperative dressings, a randomized trial was conducted in 90 male and female patients. 44 patients had the transparent adhesive drape and 46 a conventional dressing. Both groups were reasonably well matched according to age, sex, height, weight and type of operation. There was no difference in healing of skin wounds. But reddening around the stitches was seen more often in patients with the conventional dressing than in those with the polyurethane drape (p less than 0.05). Surprisingly, most of the patients with the transparent drape (42 of 44) accepted it. The transparent adhesive drape was found to be much less expensive than the conventional dressing.