Objective: To compare between L pharyngeal flap alone and combined L pharyngeal flap with phenytoin for repair of palatal fistula and velopharyngeal insufficiency (VPI). Methods: Twenty patients with soft palate fistula and persistent VPI who were divided into two groups. In the first group, superiorly based L pharyngeal flap was harvested from the oropharynx and inserted into the soft palate to close the fistula after fistula trimming. In the second group, the same L flap was done plus submucosal injection of phenytoin. Patients were evaluated before and after surgery using video-nasoendoscopy, and speech analysis. Results: In all patients, the palatal fistula could be closed. The nasal emission, intraoral pressure, resonance and articulation defects improved significantly after surgery, according to postoperative speech evaluation. All patients achieved grade 4 velopharyngeal valve closure (complete closure) in both groups. There were no reports of obstructive sleep apnea or flap dehiscence (partial or total).Both groups showed significant improvement of speech postoperatively with more improvement with topical phenytoin. Conclusion: Submucosal injection of phenytoin during repair of VPI and palatal fistula using L pharyngeal flap as a single stage surgery appears safe and seems to enhance healing, helping to close palatal fistula and correct velopharyngeal functions (closure and speech) in patients with persistent VPI with no reported significant complication