Application of hyaluronan (HY) in periodontal treatment has recently increased due to its bacteriostatic and anti-in ammatory pro- perties. This review is based in part on a recent systematic review and also includes newly published studies such as those on gingivitis patients. It summarizes the thera- peutic possibilities of HY application as a monotherapy and as an adjunct in the treatment of gingivitis and periodontitis. Based on literature searches in 3 databases, 18 controlled trials were identi ed. When comparing the HY test group with the control group, the majority of the clinical trials reported (a) a signi cant improvement in gingival indices of gingivitis patients and (b) a signi cant but clinically moderate reduction in bleeding on probing and probing pocket depth after nonsurgical treatment of periodontitis patients. The effect of HY application on clinical attachment level gain after surgical regenerative treatment remains unclear. Because no unexpected side effects were reported after HY-application, its use can thus be considered safe. However, due to the considerable heterogeneity of the available studies, in terms of product diffe- rences and varying application modalities, no recommendation can be provided re- garding the appropriate HY administration or the effective amount for the treatment of gingivitis or periodontitis.