AIM: To evaluate long term complications after pterygium excision with mitomycin C (MMC) application. DESIGN: Prospective non-comparative interventional case series. PARTICIPANTS: Ninety nine patients who underwent pterygium surgery and participated in a controlled study for efficacy of MMC for pterygium surgery between 1989 and 1994. METHODS: Patients who were located and agreed to come for examination underwent a complete eye examination. The bare sclera area, in particular, was examined for possible complications. The main outcome measures were anatomical findings in area of MMC application. RESULTS: Forty three eyes of 43 patients were examined. Sixty three per cent of patients had pterygium surgery with intraoperative application of 0.02% MMC for 5 minutes and 37% of patients received MMC 1% or 2% drops four times daily for 2 weeks postoperatively. In three patients, pterygium recurred within 18 months. The only complication was mild conjunctival avascularity in areas of pterygium excision in 30% of patients. CONCLUSION: Long term evaluation revealed that the use of MMC in pterygium surgery is safe, but for a strict selection of patients, controlled use of MMC and long term follow up are required.