Background: The purpose of this study is to compare the effects of twodifferent doses of 5-fluorouracil (5-FU) on closure rates and histopathological findings in myringotomyto those of simple myringotomy with saline application. Material/Methods: 36 rats were divided into twostudy groups and a control group of 12 rats each. After bilateral myringotomy, we applied 5-FU 50 mg/mlin group A, 10 mg/ml in group B and saline in the control group for 10 minutes. Examination was madeby otoendoscopy on days 1, 3, 5, 7, 10, 15, 20, 25. After the follow up examination, two rats from eachgroup were randomly sacrificed on days 7, 15, 25 and 35. Both tympanic membranes were investigated forfibrosis and inflammation by light microscopy. Results: Most of the tympanic membranes from group B andthe control group healed on the 10(th) day, but 16 myringotomies were patent in group A; by the 25(th)day, all myringotomies in all three groups were completely healed. The mean healing time was 14.62 days,10.20 days and 10.40 days respectively in groups A, B and control. Fibrosis and inflammation were lessin group A than in group B and the controls. Conclusions: 5-FU at a concentration of 50 mg/mL is effectivein prolonging the patency of myringotomies in rat tympanic membranes, while a concentration of 10 mg/mLhas no greater effect than a simple myringotomy procedure with saline application.

Keywords: Antimetabolites - administration & dosage, Dose-Response Relationship, Drug, Fibrosis, Fluorouracil - administration & dosage, Inflammation - prevention & control, Middle Ear Ventilation - methods, Otitis Media with Effusion - surgery, Tympanic Membrane - surgery, Wound Healing - drug effects