Proximal radioulnar translocation with radial neck fracture and elbow dislocation is extremely rare. We report a case of a 5-year-old boy who was presented with elbow dislocation, and proximal radioulnar translocation was diagnosed a day after the injury. Mini-open technique was used to reduce the translocation and radial neck fracture. The patient finally regained full range of elbow motion and forearm rotation. This case had clinical importance in that the reverse instability of the elbow was observed compared with the previous reports.