Background: Trabeculectomy is the most common surgical treatment for glaucoma in which a filtering fistula is created with the aim of lowering the intraocular pressure (IOP). A slow healing response of the surgical wound is important for a successful surgery and Beta irradiation is a rapid, effective and simple treatment to slow down this healing process. This study, evaluates the intraocular pressure lowering effect of beta irradiation as an adjunct to trabeculectomy in Nigerians. Methods: A retrospective study of patients aged ≥ 21years with preoperative IOP ≥ 21mmHg who underwent trabeculectomy with beta irradiation for glaucoma between 2012 and 2017 and had a minimum of 2 years follow up at Eleta Eye Institute and Ojulowo Eye Clinic in Ibadan, Nigeria. Seventy-one eyes of 54 patients were analyzed. They underwent trabeculectomy with adjunct beta irradiation which was administered intraoperatively on the conjunctiva overlying the bleb area as a single dose of 2,400cGy using a strontium-90 probe. All the 54 patients were operated on by the same surgeon. Results: 64.8% of the patients were males and the mean age for the patient was 45±3.7. 66.2% eyes had preoperative VA ≤ 6/18 while 91.5% eyes were able to maintain the pre-operative VA three months post operation. Mean preoperative IOP was 25.0±4.6mmHg, 10.5±2.3mmHg at 1 month post operation and 14.5±3.5mmHg at 2 years post operation. There was a statistically significant difference in the preoperative and postoperative IOP after 2 years, P value <0.05 Conclusion: Trabeculectomy with beta irradiation gives a good control of intraocular pressure and is recommended in patients at risk of developing post-operative conjunctival fibrosis.