PURPOSE: Chlorhexidine (CHX) is an antimicrobial agent used in the prevention of tooth decay, periodontal disease, and postextraction alveolar osteitis (AO). Recently, a bioadhesive gel to deliver the active substance, CHX, was introduced. The intra-alveolar placement of the bioadhesive gel allows a more direct and prolonged therapeutic effect of CHX, which is useful in the prevention of AO after extraction of impacted third molars. The intra-alveolar application of the bioadhesive CHX gel in patients with bleeding disorders may increase the risk of postoperative bleeding complications. Inversely, bleeding disorders might influence the efficacy of CHX for AO prevention. The purpose of the present study was to evaluate the effectiveness of the bioadhesive 0.2% CHX gel in reducing the incidence of impacted third molar postextraction AO in patients with bleeding disorders. MATERIALS AND METHODS: We performed a double-blind, randomized, parallel-group study of 38 patients with bleeding disorders. The experimental group (n = 14) was treated with bioadhesive 0.2% CHX gel applied intraoperatively once after surgical removal of the third molar. The control group (n = 24) was treated in an identical fashion with placebo gel. RESULTS: We observed a 57.15% reduction in the incidence of AO in the experimental group. The control group had a 17% incidence of AO and the experimental group had a 7% incidence of AO (P = .402). Bleeding complications occurred in 21% of the experimental group compared with 29% of the control group (P = .601). CONCLUSIONS: As described in previous studies, the single intra-alveolar application of the bioadhesive 0.2% CHX gel in an intraoperative fashion seems to reduce the incidence of AO after removal of impacted third molars in patients with bleeding disorders. On the basis of the reported percentage of bleeding complications, the routine use of postoperative local hemostatic measures is recommended.