As THE UNITED STATES POPULATION AGES, people will be taking more medications which may benefit their general health but not necessarily their periodontal health. The effects of medications have been grouped into six categories as follows: behavioral alteration of oral hygiene methods, alteration of plaque composition, effect on gingival tissues, effect on alveolar bone, effect on gingival crevicular fluid, and effect on salivary flow. Although most medications discussed in this paper increase the risk for periodontal disease, a few may actually decrease the risk. These include the effect of phenytoin on alveolar bone, the antibacterial effect of antibiotics, the anticollagenolytic effects of tetracyclines, and the effect of non-steroidal anti-inflammatory drugs on decreasing alveolar bone resorption.