Purpose: Molteno implants remain popular for treating recalcitrant glaucomas. This study aimed to assess the effect of mitomycin C (MMC) use with Molteno tube implantation upon intraocular pressure (IOP) control and complication rates. In particular, the study aimed to assess any change that MMC might have upon the postoperative hypertensive phase.Methods: A retrospective case record study was conducted of all patients undergoing double plate Molteno implant surgery by one surgeon over 5 years. Eyes with recalcitrant glaucoma unresponsive to previous surgery, or deemed unlikely to succeed with trabeculectomy, underwent double plate Molteno tube implantation. Eyes that had MMC (0.3 mg/mL, 3 min) applied to Tenon's capsule over the secondary plate were compared with eyes that underwent surgery without adjunctive MMC application.Results: Twenty-seven eyes received MMC and were similar to 26 eyes not receiving MMC in terms of glaucoma subtype, age, sex, previous surgery, preoperative IOP and postoperative IOP lowering agents. Those not receiving MMC had raised IOP 31-90 days post implantation compared with MMC treated eyes (P < 0.01) and more often received oral antifibrosis medication (P < 0.05). Complications were no more common with MMC except for initial overdrainage. Significant systemic complications from the use of oral antifibrosis medication were common.Conclusions: The findings suggest a useful role for MMC. Caution is advised in case selection for MMC use. Mitomycin C treatment over the secondary plate alone permits removal of this plate if MMC-related complications occur without requiring removal of the whole implant.