Objectives: Close approximation and stabilization of gingival flaps, vital for optimum outcome of surgical procedures, may be difficult to achieve in deep periodontal pockets by routinely used suturing techniques. Modified vertical internal mattress sutures have been reported to be useful in reducing dead space along with achievement of wound stability. The present study compares the outcome of flap closure by use of modified vertical internal mattress sutures and simple loop interrupted sutures in the surgical management of chronic periodontitis. Method and materials: In total, 83 participants with chronic periodontitis received scaling and root planing. After 8 weeks, modified Widman flap surgery was performed in 48 patients at sites with probing pocket depth ≥ 4 mm. Modified vertical internal mattress sutures were placed in the test group (n = 24) and simple loop interrupted sutures were used in the control group (n = 24). Plaque Index (Silness and Loe), Gingival Index (Loe and Silness), bleeding on probing, probing pocket depth, clinical attachment level, and gingival recession were recorded on the day of surgery, and at 3 and 6 months of follow-up. Results: Statistically significant improvement was noted in all the clinical parameters of both groups. The test group showed significantly greater improvement in probing pocket depth, clinical attachment level, bleeding on probing, and Gingival Index, although Plaque Index scores were similar. This improvement was confined to nonmolars only. Conclusion: Flap closure by modified vertical internal mattress suturing technique results in better improvement in periodontal clinical parameters than the use of simple loop interrupted sutures, especially in nonmolars. Keywords: chronic periodontitis, modified Widman flap surgery, surgical flaps, sutures, wound healing