Thirty hemorrhagic periodontitis adult patients completed a 90-day controlled clinical study to determine the clinical effects of the antiinflammatory preparation neopredin gel containing prednisolone, neomycin sulfate and chlorhexidine when used an adjunct to scaling and root planing. The results were evaluated using the Quigley-Hein plaque index, the Schour-Massler gingival bleeding index, the Svrakov-Pissarev gingival vital staining index, the Muleman-Son sulcus bleeding index and the percentage of bleeding on probing sites. Treatment with neopredin resulted in consistently lower values of the mean plaque index score, the gingival bleeding index score, the vital staining index score and the sulcus bleeding index score at days 14.30 and 90. A significant reduction in the mean pocket probing depth was observed at day 30. The first symptoms of recurrent gingival inflammation were noticed at day 90. Our results indicate that neopredin is effective in reducing supragingival plaque accumulation, gingival inflammation, bleeding on probing and periodontal pocket depth and these reductions are highly significant.