Objective: The objective of the present systematic review and meta-analysis was to compare treatment with membrane associated with bone grafting and treatment exclusively with membrane in the approach of Class II furcation defects in mandibular molars. Materials and Methods: The Preferred Reporting Items for Systematic Reviews and Meta-analyses statement was followed. Searches were conducted in five databases (PubMed, Web of Science, Scopus, Ovid, and Lilacs), in Septem-ber 2021, without restriction regarding publication year or language. Studies comparing membranes associated with bone grafting and membranes exclusively in the treatment of Class II furcation lesions were included. Cross-sectional, case-control studies, and reviews were excluded. Study selection, data extraction, and risk of bias assessment (MINORS) were performed by two review authors. The certainty of the evidence (GRADE) was evaluated and meta-analysis was performed. Mean difference (MD) and 95% confidence interval (CI) were provided. Results: Four hundred eighty-six references were iden-tified and four studies were included. Greater reduction in probing depth [MD = 0.32 (CI = 0.09, 0.56)] and greater clinical attachment level gain [MD = 0.41 (CI = 0.24, 0.57)] were observed when membrane and bone grafting were used. The risk of bias of included studies was low. Conclusions: This present systematic review and meta-analysis demonstrated that treatment of Class II furcation defects in mandibular molars using membrane and bone grafing is significantly more efficacious than treatment with the exclusive use of membrane. Keywords: Periodontitis; Bone grafting; Membranes; Guided tissue regeneration; Furcation defects; Systematic review