Intraoperative mitomycin C has been shown to be highly effective in increasing the success rate of glaucoma filtration surgery. Between October 1991 and June 1992, 169 eyes of 156 patients underwent filtration procedures with intraoperative mitomycin C. In the postoperative period, five eyes (2.9%) developed hypotony maculopathy, characterized by disc edema, vascular tortuosity, and chorioretinal folds in the macular area. Cryotherapy was applied to three eyes, and was effective in reversing the hypotony in two of them. However, the visual prognosis was poor: after a mean follow up of 5.3 months (range, 3.5 to 8 months), visual acuity returned to preoperative levels in one case. Hypotony maculopathy may develop after glaucoma filtration surgery with intraoperative mitomycin C. We suggest restricting the indication of its adjunctive use to eyes with poor surgical prognosis or those in which a very low intraocular pressure is desired. The use of extra sutures (which can be sectioned by laser) or releasable sutures to prevent excessive filtration in the postoperative period also is advisable.