Objectives: Retrospective study to evaluate the short term outcome and contributing prognostic factors of trabeculectomy in terms of intraocular pressure in Omani patients of South Batinah region with primary open-angle glaucoma. Methods: This study involved retrospective evaluation of 18 patients (22 eyes) with primary open angle glaucoma who underwent primary trabeculectomy between February 2005 and February 2008. All patients were aged over 40 years and were Omani. Follow-up for all subjects lasted at least 6 months or more [Average follow up 388 days with standard deviation of 182]. Successful control of Intraocular pressure (IOP) was defined as achieving IOP of 21 mmHg or less without medication (complete success). Results: The results are presented with particular emphasis being placed only on intraocular pressure (IOP) control. The tonometric success rate of trabeculectomy in controlling the IOP at 21mmHg or less without any medication was 46% [complete successes], 18% had qualified success [Post operative IOP 21 mm Hg or less with one topical medication], while 36% trabeculectomies failed to show desired results. Conclusion: The results of this retrospective study underline that the procedure of trabeculectomy has moderate success in controlling the intra ocular pressure in the study population. The procedure failed to show the desired result in almost one third of the patients (36%) and topical medical treatment was reinstated in these patients with either two or three drugs. However these results lead to the following question: Should trabeculectomy be the therapy of first choice in the early stage of glaucoma?