Objective: Ventilation tubes are used to a large extent for the treatment of otitis media with effusion. As this has some drawbacks, laser myringotomy was suggested as a treatment alternative. The use of laser has some advantages but its use is limited in prolonging the patency rate of myringotomy. Mitomycin C (MMC) is being used in some surgical applications to reduce stenosis as it has the property to inhibite activity of fibroblasts. We explored the use of mitomycin C as an adjunct in prolonging the patency rate in laser myringotomy on rats. Methods: We performed laser myringotomy on both ears of 20 rats. We, then applied MMC with a concentration of 2 mg/ml on 10 rats to one of their ears (Group 1). In group 2 we used MMC with a concentration of I mg/ml. After a follow-up of 8 weeks we calculated the patency rate for the two groups and the total ears with MMC and without MMC. Results: The mean patency rate observed for group 1 was found to be 6 weeks whereas for group 2, it was 5.8 weeks. The overall patency rate for the ears with and without MMC is 5.9 and 1.5 weeks, respectively. While there was a statistical difference between ears with and without MMC (P < 0.01), there was no difference between the two groups according to concentrations. Conclusion: Mitomycin C has an adjunct effect in laser myringotomy in prolonging the patency rate of myringotomy on rats. Low concentrations of mitomycin C have the same effect in this issue. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.