To evaluate the efficacy of the 175-mm2 Molteno3 implant in patients with nonneovascular glaucoma. A hospital-based, retrospective historical control comparative case series comparing results in the first 87 eyes to receive the 175-mm(2) Molteno3 implant with those in a control group of 115 eyes receiving the 274-mm(2) double-plate Molteno implant. Success was defined as an intraocular pressure (IOP) of at least 6 mm Hg but not more than 21 mm Hg with or without hypotensive medication. The mean postoperative follow-up was 3.0 years (range, 13 days to 5.6 years) in the Molteno3 implant group and 6.2 years (range, 1 day to 13.9 years) in the double-plate Molteno implant group. The mean (SD) preoperative IOP was 25.6 (7.1) mm Hg in the Molteno3 implant group in eyes treated with a mean of 2.3 ocular hypotensive medications, and 25.7 (8.0) mm Hg in the double-plate Molteno implant group in eyes treated with a mean of 2.2 medications. The mean (SD) postoperative IOP at 36 months was 13.9 (3.2) mm Hg in the Molteno3 implant group in eyes treated with a mean of 0.9 ocular hypotensive medications, and 14.5 (3.4) mm Hg in the double-plate group in eyes treated with a mean of 0.7 medications. The probability of IOP control at 3 years was 0.79 in both groups. There was significantly more postoperative hypotony in eyes without a polyglactin 910 tie in the Molteno3 implant group (P= .04); however, significantly more eyes with flat anterior chambers in the double-plate group required anterior chamber reformation (P= .03). The 175-mm(2) Molteno3 implant provided intermediate-term successful treatment of nonneovascular glaucoma comparable to that provided by the double-plate Molteno implant.