Background: Open reduction and plate fixation are the preferred treatment options for most distal humerus fractures in adults. However, it is often challenging for orthopedic surgeons because of the complex anatomy and the difficulty in achieving stable fixation. This multicenter study aimed to analyze the complication types and rates of patients with distal humerus fractures treated with open reduction and plate fixation, and compare the results with those found in the literature. In addition, we describe the clinical outcomes.Methods: This retrospective multicenter study was conducted between September 2001 and March 2021, and included data from four hospitals. In total, 349 elbows underwent surgical treatment at these hospitals during the study period. Patients >17 years of age who were treated by plate fixation were included, and patients who were treated by other fixation methods were excluded. A total of 170 patients were included in the study. The following types of complications were investigated: (1) nerve-related; (2) fixation- and instrument-related; (3) osteosynthesis-related; (4) infection; and (5) others.Results: The following complications were found: (1) 26 (15.3%) cases of postoperative ulnar nerve symptoms; 4 (2.4%) of postoperative radial nerve symptoms; (2) one (0.6%) case of screw joint penetration and screw loosening; and eight (4.7%) cases of hardware removal due to instrument skin irritation; (3) seven (4.1%) cases of nonunion; (4) two (1.2%) and four (2.2%) cases of superficial and deep infection, respectively, and seven (3.9%) cases of wound complication; and (5) 37 (21.8%) cases of heterotrophic ossification, 79 (46.5%) cases of elbow stiffness (did not achieve functional range of motion [ROM]), and 41 (24.1%) cases of osteoarthritis over Broberg and Morrey Grade I.Paradoxically, the postoperative ulnar nerve symptoms were more frequent in the prophylactic ulnar nerve anterior transposition group. However, this difference was not statistically significant (p = 0.086). The mean ROM was 123.5° flexion to 9.5° extension. The average Disabilities of the Arm, Shoulder and Hand (DASH) score was 14.5±15.6.Conclusions: Open reduction and plate fixation for distal humeral fractures is a reasonable treatment option with acceptable complication rates and favorable clinical outcomes. Surgeons must be vigilant about ulnar nerve complications.Level of Evidence: Therapeutic Level III