BACKGROUND Cleft lip/palate is a facial anomaly caused by an abnormal developmental process. It is also the most common congenital anomaly. Orthognathic surgery is required in 25% of patients with cleft lip and palate for the correction of dentofacial deformity. There are various complications that can occur after orthognathic surgery. Complications that can occur during surgery include bleeding, improper fracture, and injuries to the inferior alveolar nerve (IAN) and lingual nerve. Meanwhile, postoperative complications include hemorrhage, edema, pain, infection, and delayed union or nonunion. This study retrospectively examines the complications that occurred after the orthognathic surgery in cleft lip/palate patients at Pusan National University Dental Hospital. METHODS From June 1, 2008 to July 31, 2017, we selected 17 patients who underwent orthognathic surgery for cleft lip/palate at the Department of Oral and Maxillofacial Surgery, Pusan National University Dental Hospital. The patients were treated at different hospitals for all operations related to cleft lip/palate. RESULTS Intraoperative complications include hemorrhage, inadequate fracture, injury to the IAN and lingual nerve, root damage, and fistula. The patients who were evaluated included 2 patients with inadequate fracture, 3 patients with injury to the IAN, and 1 patient with fistula. Postoperative complications (e.g., as damage of the inferior alveolar nerve and velopharyngeal insufficiency) may occur, and all patients recovered during the follow-up period of 6 months or more after the surgery. The relapse rates were A-N per 14.0%, Pog-N per 15.1%, SNA 24.4%, and SNB 4.6%. There was no statistically significant difference in relapse rate. CONCLUSIONS Complications that may occur after the orthognathic surgery in the patients with cleft lip/palate are similar to those without cleft lip/palate.