Objective: To investigate the prevalence of gingival overgrowth and the risk factors in epileptic patients attending out-patient clinic of Neurology Department of Lagos University Teaching Hospital, Idi-Araba, Lagos, Nigeria. Method: 300 dentate subjects consisting of 150 epileptics and 150 control subjects matched for age and sex participated in this study. Bio-data and medical history were collected using a questionnaire and confirmed from patient case file. The Simplified Oral Hygiene Index (OHI- S) of Greene and Vermillion and Gingival Index were used to assess the oral hygiene status and gingival inflammation respectively. Presence or absence of gingival hyperplasia was also recorded. The Epi Info (version 6) statistical software was used for data entry, validation and analysis. Results: Mean age for the epileptic and control groups were 31.5 + 16.5 years and 31.3 +16.4 years respectively The mean Oral Hygiene Index score for epileptic and control groups were 1.89 + 0.758 and 1.55+ 0.864 respectively. The differences in OHI-S score and prevalence of gingival hyperplasia between the epileptics and control group were statistically significant (p-value <0.05). Development of gingival overgrowth was found to be significantly related to gingival index score and phenytoin therapy (p<0.000). Conclusion: Our findings confirm reports from previous studies that gingival inflammation and phenytoin therapy are significant risk factors in the development of gingival overgrowth.