Objective Clinical effects in local application of hyaluronic acid (HA) adjunctive to scaling and root planing (SRP) were evaluated.Methods In this cross over design study 20 patientswith chronic periodontitiswere included. Plaque in- dex, sulcus-fluid-flow-rate (SFFR), sulcus bleeding index, probing pocket depth and attachment level were monitored. All pa- tients were treated with full mouth SRP, in addition a HA gel was administered subgingivally in the test site every week for 6 weeks.Results A statistically significant improvement of all clinical test parameters was observed in both groups (P