Purpose: To determine the causes of high intraocular pressure post-trabeculec-tomy. Methods. A restropective analysis of 159 eyes of 137 cases with trabeculec-tomy was made. Results. High intraocular pressure was recorded postoperatively in 21 eyes of 19 cases. The incidence was 13.21%. Among them, There were 8 eyes (38.1%) with filtering hole but without filtering bleb. 5 eyes (23.81%) with filtering hole blocked by clots and fibrotic tissues. 4 eyes (19.05%) with both filtering hole and bleb. 1 eye (4.76%)with filtering hole blocked by iris, 1 eye (4.76%) with filtering hole blobked by lens....