The study evaluated, clinically and microscopically, the soft tissue response of suprabony periodontal pockets treated by root planing and oral hygiene or by oral hygiene measures alone. The participants were 22 adults beginning treatment for inflammatory periodontal disease. For each patient, three clinically similar labial or lingual pockets were scored for gingival inflammation, pocket depth, and the extent of plaque and calculus. One pocket in each patient served as a control, and a gingival biopsy was obtained to determine the pretreatment level of inflammation. The second pocket was treated by root planing and by the patient's oral hygiene measures. The third pocket was treated only by the patient's daily oral hygiene measures. Fifty-six to 63 days later, treated areas were reevaluated clinically, and biopsies were secured. Each type of therapy reduced the mean pocket depth and the incidence and severity of gingivitis; however, root planing accompanied by oral hygiene measures resulted in a statistically greater improvement than did oral hygiene measures alone.