Periodontal disease continues to be one of the principle problems of mankind. It has been well established that the periodontal disease is the result of local bacterial infection with a pathogenic microflora within the periodontal pocket. Conventional method for the elimination of subgingival microbial infection includes mechanical debridement of plaque from root surfaces. However, the effectiveness of these conventional treatments is limited by the lack of accessibility to bacteria in deeper periodontal pockets. As the results achieved by standard therapy are inconsistent, a concept of chemotherapeutic plaque control has assumed increasing importance to the clinician. This comprehensive review covers the detailed information of various local drug delivery systems used in Periodontics, principles & rationale of antimicrobial therapy, design of local drug delivery systems & their clinical implications in Periodontology. Formulated local drug delivery systems in the field of Periodontology are used particularly in medically compromised patients with mild to moderate periodontitis where periodontal surgical procedures are contraindicated.