Introduction: In this case, we discuss a patient with a neglected and malunited both-bone forearm fracture with distal radioulnar joint dislocation. This pattern of fracture by itself is uncommon, but the initial negligence of this trauma makes it even more rare and challenging for surgical treatment. Case report: The main aim of the surgery was to restore the forearm's function and anatomy. After thorough preoperative preparation, including planning the level of resections, the patient was treated with open reduction and internal fixation with a limited contact dynamic compression plate. The distal radio-ulnar joint was fixed with 2 K-wires. On control follow-up six months later, the resection sites were fully consolidated, with no visible deformation of the forearm. Pronosupination was restored up to 60% of normal functional arc. Conclusion: This case has shown that even with careful restoration of forearm anatomy, results of the surgical treatment in neglected and malunited both-bone forearm fracture with distal radioulnar dislocation will not be a priori good or excellent. Surgeons need to remind the patients that the return of the function of the upper limb to the degree before the trauma cannot be guaranteed.