The clinical results achieved were compared when a group of 21 patients requiring gingivectomies in comparable bilateral segments received a dressing or a chlorhexidine mouthwash during the first post-operative week. Initial pre-operative conditions were comparable. In each of the two treatments highly significant reductions in pocket depths were achieved; the sizes of the reductions were of clinical significance (greater than 1.5 mm). The observed difference (0.16 mm) between the two treatments in favour of the mouthwash, although significant at the conventional 5% level, was clinically unimportant. More patients preferred the dressing as a post-operative treatment, and the clinical implications of the patients' preferences are discussed.