Objective: Connective tissue grafts (CTGs) have been used as a barrier for closing mandibular Class II furcation defects. The present study compared long-term (48 months) effectiveness of CTG as a barrier with bioresorbable collagen membrane in the treatment of mandibular Class II furcation defects in humans. Method and Materials: Twenty chronic periodontitis patients with a single Class II furcation defect on the buccal surface of mandibular teeth were included in the study. Vertical probing pocket depth (V-PPD), vertical relative attachment level (V-RAL), and relative gingival margin level (RGML) were recorded at baseline, 6 months, 12 months, and 48 months post-surgery. Results: The mean V-PPD reductions observed in the test group and control group were statistically significant at all time intervals when compared with the baseline. Similarly, the mean V-RAL gain at 6 months, 12 months, and 48 months were statistically significant, compared with the baseline data in both the groups. At 48 months the difference in V-RAL gain between the groups was found to be statistically significant, with greater improvements in test group. Complete closure of furcation and improvement in horizontal classification were better in the test group than in the control group. Conclusion: It can be concluded that both treatment modalities result in improvement in clinical parameters. However, the results obtained with CTG appeared to be more stable. Schlagwörter: Class II furcation, collagen membrane, subepithelial connective tissue graft