Gingival overgrowth (GO) is one of many side effects of phenytoin (PHE) antiepleptic agent. The aim of this study was to evaluate the development of peiodontitis in patients taking PHE and its relation with GO, age, duration of drug administration. Thirty-four patients (14 females, 20 males: range 9-49 years; mean age 29.5) undergoing PHE treatment (range 2-32 years; mean 11.8) from the department of periodontology, faculty of dentistry, Damascus University was included in the study. Medical history including drug duration and clinical measurement of GO index, probing depth (PD) periodontal pocket bleeding points index (BPI) and panoramic radiographs for bone loss (BL), were performed for each patient. For statistical analysis Correlation test (r) was used to determine the correlation between age, duration and periodontal indices.