<b>Patient:</B> A 61-year-old male presented with the chief complaint of difficulty in chewing caused by missing lower teeth. In this case, radiation therapy (malignant lymphoma) was performed for the left mandible, and three implants were inserted in the right mandible. An overdenture (Konus telescope denture) was selected for the final prosthesis.<br><B>Discussion:</B> The final prosthesis had mechanical problems. A complicated design of the prosthesis was necessary to achieve satisfactory esthetic and functional results. Frequent periodic observation and re-evaluation are needed.<br><B>Conclusion:</B> Functional problems caused by loss of occlusal support were successfully rehabilitated using an implant-retained removable partial denture.