We reviewed the charts of 60 consecutive patients with open-angle glaucoma who underwent a trabeculectomy (T) or a single-site combined glaucoma and cataract procedure (phaco-trabeculectomy = PT) to compare the pressure lowering effect of both techniques. The pressure lowering effect after 12 months was significant in both groups: 11.44 +/- 5.94 mm Hg in the T-group and 5.00 +/- 4.51 mm Hg in the PT-group (p < 0.001). The pressure levels one year postoperatively were significantly lower in the T-group compared to the PT-group: 11.08 +/- 2.80 mm Hg versus 15.04 +/- 2.40 mm Hg (p < 0.001). Our results suggest that the combined procedure, although proven to be effective in lowering the intraocular pressure, is less effective than trabeculectomy alone.