AIM: The study aim was to investigate the predictive role of obesity on clinical response following non-surgical periodontal therapy in individuals with severe periodontitis. METHODS: 57 BMI obese and 58 BMI normal non-smoker adults with periodontitis (defined as probing pocket depths (PPD) of ≥5 mm and alveolar bone loss of >30% with >50% of the teeth affected) received non-surgical periodontal therapy. Periodontal status was based upon PPD, clinical attachment level(CAL), and full mouth bleeding score(FMBS). Mean PPD, percentage sites PPD>4mm, percentage sites PPD>5mm, and FMBS at 2 and 6 months were outcome variables. Propensity score analysis was used to assess the effect of obesity on outcome variables after adjusting for confounders. RESULTS: Statistically significant higher clinical measures (mean PPD, mean percentage of sites with PPD>4mm, mean percentage of sites with PPD>5mm, and FMBS) were observed in the obese group than the normal group at baseline, 2 and 6 months after therapy(p4mm(p5mm(p<0.05), and FMBS (p<0.01), independent of age, gender, ethnicity or plaque levels. CONCLUSIONS: Obesity compared to normal BMI status was an independent predictor of poorer response following non-surgical periodontal therapy