Local antibiotic delivery is preferred for treating periodontitis due to the benefits of high local drug concentration and minimal side effects. However, commercial polymeric drug delivery systems lack bioactivity and need additional bone grafting to treat the periodontal bone loss. In the present work, calcium deficient hydroxyapatite (CDHA) nanoparticles incorporated gelatin-alginate (GA) films were developed as antibiotic releasing bone substitutes for treating infrabony periodontal defects. CDHA nanoparticles (<50 nm) were incorporated into GA polymer blend films prepared by solvent casting method. The degradation rate and ease of handling were controlled by optimising the concentration of polymer solution and CDHA. The effect of loading methodology on the drug release was studied by adding the antibiotic tetracycline to a) polymer blend, b) CDHA, c) polymer CDHA solution and d) both CDHA and polymer blend. Tetracycline loading on polymer matrix resulted in nearly 100% burst release while an incomplete release (40%) was observed from tetracycline loaded CDHA. Sustained drug release for 10 days suitable for treating severe periodontal infections was obtained on equal drug distribution between the polymer blend and CDHA. The bioactive CDHA incorporated GA composite films can provide sustained tetracycline release for the treatment of periodontal infections. © 2017 Elsevier B.V.