The mesh plug technique for adult inguinal hernia repair is easy to perform and results in a good postoperative quality of life. It allows inguinal hernia surgery to be performed as day surgery, but some problems may occur. We performed day surgeries tp repair 110 adult inguinal hernias, and the results are reported here. The procedures are as follows. Under local anesthesia, the inguinal canal and hernial sac are freed. Then the internal ring and the weakness of the posterior wall are estimated. The plug is inserted and then the mesh is on layed. As a result, all of our cases were successful under local anesthesia. After surgery, 5 subcutaneous hematomas occurred. Six patients required subsequent hospitalization: one because of subcutaneous hematoma; and 5 for pain control. In summary, the mesh plug technique under local anesthesia for adult inguinal hernia repair is a useful method for day surgery, but some an on-call system after surgery is necessary and hospitalization for postoperative complications may be required.