Objective: The aim of this study was to evaluate the efficacy and safety of trabeculectomy performed with mitomycin C (MMC) at a concentration of 0.2 mg/mL for 3 minutes in glaucoma patients with high risk of surgical failure. Methods: Forty-seven eyes of 45 patients (30 male, 15 female) undergoing glaucoma filtration surgery using MMC were retrospectively reviewed. All patients who had chronic closed angle, neovascular, aphakic, pseudophakic, pseudoexfoliation glaucoma and glaucoma after keratoplasty had a high risk of surgical failure. During standard trabeculectomy, triangular sponges impregnated with MMC at a concentration of 0.2 mg/mL were applied to tenon and episcleral space in sub-conjunctival regions and under the scleral flap for 3 minutes. Postoperative IOP, appearance of filtration bleb, anterior chamber depth, leakage detected with Seidel test and other complications were recorded. The patients were evaluated on the 1st day, 1st week, 1st month, 3rd month, 6th month and 12th month. Results: The mean preoperative IOP values of patients with a mean age of 64.5 (7-83 years) were 31.6 mmHg (17-60 mmHg). Mean postoperative IOP values of patients were 15.08 mmHg at 1st week, 15.32 mmHg at 1st month, 15.57 mmHg at 3rd month, 16.42 mmHg at 6 months, 16.28 mmHg at 12 months, and 16.87 mmHg at the last follow-up. Conclusion: For eyes with high risk of surgical failure, trabeculectomy performed with MMC at low dose and optimal time is an effective and reliable method with high success rate. [ABSTRACT FROM AUTHOR]