Objective — to assess potential of preoperative therapy with local steroid and non-steroid anti-inflammatory drugs (SAIDs and NSAIDs) for prolonging the hypotensive effect of trabeculectomy. Material and methods. A total of 80 patients with primary open-angle glaucoma planed for trabeculectomy were randomized into 4 groups of 20 each: 3 groups that differed in the studied drug (nepafenac, dexamethasone, or their non-fixed combination) and a control group with no preoperative therapy. The patients instilled 1 drop of either drug b.i.d. for 2 weeks before the surgery and were examined each day of the first week and then at weeks 1, 2, 4 and months 3, 6, and 12. The rate of postoperative surgical and medical interventions (needling, needling revision, hypotensive therapy) was used for outcome evaluation. Results. Postoperative needling was required in 50% of the controls, 35% of the NSAIDs and 30% of the SAIDs patients as well as 20% the combination-therapy patients. Needling revision had to be performed in 10% of patients from the control group and 5% of patients from the NSAIDs group. Patients from the steroid and combination-therapy groups had no need in needling procedure. Further hypotensive therapy was required in 50% of the control group, 35% of the NSAIDs group, 25% of the SAIDs group and 20% of the combination-therapy group. During the first postoperative year complete success of the treatment was achieved in 50% of the controls, 65% of the NSAIDs patients, 75% of the SAIDs patients, and 80% of those under combination therapy. Qualified success during the same period was achieved in 100% of cases. Conclusion. Preoperative local anti-inflammatory therapy helped to increase the one-year complete success rate after trabeculectomy as compared with the controls. The most significant hypotensive effect was noted in the combination-therapy group (80%), less significant — in the steroid and non-steroid monotherapy groups (75% and 65% correspondingly). A negative correlation was noted between the use of nepafenac and dexamethasone and other measures aimed at increasing the hypotensive effect of glaucoma surgery.