Purpose To compare the IOP lowering and intra- and postoperative complications of the trabeculectomy versus deep sclerectomy. Patients and method Prospective study of 28 patients with medically uncontrolled symmetrically primary open angle glaucoma in which randomly was performed trabeculectomy on one eye and nonpenetrating deep sclerectomy on the other eye. The same surgeon operated both eyes in a 6 weeks interval at most. The IOP measurements (in a 24 hours period) were recorded at 1 week, 1,3,6,12,18 and 24 months. The incidence and gravity of the intra- and postoperative complications as well as the need postoperative medical antiglaucoma therapy were compared between the two groups. The mean follow-up period was 24.2 ± 8.6 months (15.6 - 32.8 months). Results The postoperative IOP values at any time during the follow-up visits were statistically significant lower in the trabeculectomy group compared with nonpenetrating deep sclerectomy group. The same was true for the need of adjuvant medical antiglaucoma therapy added postoperative. The incidence and gravity of the intra- and postoperative complications was lowers in the nonpenetrating deep sclerectomy group. Conclusions The trabeculectomy lowers the IOP more than the nonpenetrating deep sclerectomy, but the complications rate and gravity are higher with this technique.