Not much is known about the side effects of mitomycin C (MMC), an anti-fibrogenetic agent, in the upper aerodigestive tract. However, its use in ophthalmology is widely known and without quantitatively important side effects. A literature review was performed for side effects of MMC in the upper aerodigestive tract. Forty-six articles, describing the use of MMC to prevent scarring, were retracted from PubMed. Thirty-two are human studies. MMC is used in different concentrations (0.1-10 mg/ml) with different application times (2-5 min) and frequencies (up to 4 times). Five hundred and thirty-eight patients were included in those publications, of whom 19 developed side effects (3.53%). No side effects developed in studies, where post-application irrigation with saline was reported. The longest mean follow-up period is 75.5 months. Direct relations between the reported side effects and MMC seem absent in most studies. Serious complications seem to occur when MMC is used in high concentrations. Unfortunately, sometimes crucial information is lacking. One patient was described who supposedly developed laryngeal carcinoma after repeated treatment of hyperkeratosis and anterior commissure webbing. Animal studies show that excessive fibrin production can lead to acute airway obstruction. In conclusion, topical application of MMC on a wound with consecutive irrigation with saline can be performed safely to prevent scar formation in circular structures of the upper aerodigestive tract. Long-term yearly control of the application site seems advisable.