Background: Mucosal ulcers are common lesions that arise from chemical damage to oral mucosa. Phenytoin is one of the promising wound healing agents that may have the ability to decrease the duration of the healing process of wounds. Objectives: To evaluate the effect of topical application of phenytoin on chemically induced buccal mucosal ulcer of albino rat. Material and Methods: 63 male albino rats were subjected to chemical ulcer, then rats were divided into 3 main groups. Group I (control): rats did not receive any treatment, right side buccal mucosa acted as a negative control (Group I -ve), while left side (ulcerated) served as a positive control (Group I +ve). Group II (plain gel) rats received topical application of plain gel twice daily on the ulcer from the day following ulcer induction till sacrification. Group III (phenytoin gel) rats received topical application of 1% phenytoin gel twice daily on the ulcer from the day following ulcer induction till sacrification. Each group was further divided into 3 subgroups A, B and C in which rats were sacrificed at 4, 7 and 12 days following ulcer induction respectively. Buccal mucosae were dissected and examined histologically and immunohistochemically. Results: Histologically, group I+ve showed complete epithelial degeneration at day 4, re-epithelization at day 7, complete regeneration at day 12. Group II showed complete epithelial degeneration day 4, re-epithelization started at day 7, partial regeneration at day 12. Group III showed beginning of re-epithelization at day 4, continuous epithelial lining at day 7, complete regeneration at day 12. Immunohistochemically and statistically, group III showed the highest anti-PCNA expression regarding positive epithelial cells followed by group II then group I+ve. Group I-ve showed the lowest mean. Conclusions: Topical application of phenytoin 1% accelerate healing of chemically induced ulcers through increased vascularization, decreased inflammatory cells and hastened re-epithelization.