This study aimed to investigate retrospectively the outcome of surgical periodontal therapy. Periodontal surgeries implemented at General Dentistry, Tokyo Dental College Suidobashi Hospital during the period of April 2010 through March 2012 were subjected to data analysis. After initial periodontal therapy, 17 clinicians performed a total of 138 periodontal surgeries in 80 patients with moderate to advanced periodontitis (31 men and 49 women; mean age 54). Cases (sites) operated were as follows: open flap debridement=102, periodontal regenerative therapy=29 (17 for intrabony defects, 12 for furcation involvements) and periodontal plastic surgery=7. Enamel matrix derivative or bone graft was used for regenerative therapy. Clinical data were analyzed focusing on the comparison between open flap debridement and regenerative therapy. At 5 months after open flap debridement, mean reduction in probing depth (PD) and gain in clinical attachment level (CAL) was 3.9 mm (range -1.0-9.0) and 2.3 mm (range -1.0-9.0), respectively. The corresponding values with regenerative therapy were 4.0 mm (range 0-8.0) and 2.8 mm (-1.0-6.0), respectively. At sites with initial PD≥8 mm, a significantly greater gain in CAL was obtained with the regenerative therapy than with flap surgery (mean CAL gain 4.3 mm vs. 2.9 mm, p<0.05). Periodontal surgery performed in our clinical setting demonstrated a favorable short-term outcome. Our data suggest the efficacy of regenerative therapy, in particular for the treatment of deep pockets.