objectives: The use of chitosan gel may be considered as a new local chemotherapeutic material for treatment of chronic periodontitis patients. This study was directed to evaluate clinical, radiographic and biochemical effects of 1% chitosan gel in the treatment of chronic periodontitis patients. Methods: 20 patients were divided into two groups. Group I: consisted of 30 sides received SRP with intrapocket application of 1% chitosan gel. Group II: consisted of 30 sides received SRP only. All patients were subjected to initial phase therapy and instructed for plaque control regimen. Then, evaluated clinically and radiographically at baseline, 3 and 6 months after treatment. The laboratory evaluation of alkaline phosphatase enzyme level was done at baseline, 3 and 6 months after the treatment. The data were collected, tabulated and statistically analyzed by SPSS (Statistical Package for Social Sciences). Results: The clinical parameters such as probing depth,clinical attachment level, plaque index and gingival index were recorded at baseline at 3 and 6 months. In all groups, highly statistically significant differences were showed in both groups at the different intervals when compared to the baseline. Plaque index between the two groups representing no statistical significant difference in group I when compared with group II at different intervals. Gingival index showa statistical significant difference in group I when compared with group II at 3 and 6 months. Probing depth show a statistical significant difference in group I when compared with group II at 3 months and no difference at 6 months. The Clinical attachment level show a highly statistical significant difference in group I when compared with group II at 3 and statistical significant difference in group I when compared with group II at 6 months. Conclusions: Intrapocket application of chitosan gel 1% appeared to be effective adjunctive in treatment of mild to moderate chronic periodontitis.