A 65 year-old man with a diagnosis of primary open angle glaucoma underwent selective laser trabeculoplasty (SLT) due to an increase in the c/d ratio, thinning of the retinal nerve fibre layer on optical coherence tomography and a high intraocular pressure (IOP) despite maximal medical therapy. Total of 100 spots (360°, 1.1 mj) were performed on his right eye. IOP was 45 mmHg at postoperative one week and the patient was started on maximal medical therapy. Despite maximal medical therapy, IOP was 30 mmHg and we decided that a filtration surgery is required. The IOP normalized after trabeculectomy. This case reveales that post-SLT IOP elevation can be a serious complication, therefore we must keep in mind that glaucomatous patients under multiple medications are at high risk for this complication and they must be informed about it.