PURPOSE: The authors examine the intermediate-term effects of adjunctive intraoperative mitomycin C (MMC) in a cohort of patients who received double-plate Molteno implants for complicated glaucomas. METHODS: A consecutive series of 21 patients who received MMC 0.5 mg/ml for 5 minutes as an adjunct to a double-plate Molteno implant was compared by life-table analysis to a historical control group of 18 patients who received either no adjunct or 5-fluorouracil (5-FU) but no MMC. RESULTS: At three years follow-up, 35% (95% confidence interval (CI), 15-57%) of patients who received MMC avoided failure criteria of intraocular pressure (IOP) less than 6 mm Hg or more than 21 mm Hg, addition of glaucoma medication, reoperation for glaucoma, or tube removal. Seventeen percent (95% CI, 4-37%) of patients in the control group at three years follow-up met similar criteria (p = 0.039). No late complications of tube erosion were seen in the MMC group. CONCLUSION: Intraoperative MMC offers an increased likelihood of a two- to three-year period of medication-free IOP control in patients undergoing double-plate Molteno implants, compared to similar patients receiving 5-FU or no adjunctive antimetabolite therapy.