In spite of continuing efforts by many researchers and clinicians to improve oral functio, the number of patients with missing teeth resulting from periodnotitis and dental caries has not substantially decreased in Korea. Patients who use removable denture have relatively insufficient masticatory function. Various dental implants have been developed by a number of researchers to improve masticatory function. This study was undertaken to investigate the maximum bite force and masticatory function after implantatioin. A total 23 patients were treated with implantation at the Dept. of oral and maxillofacial surgery, college of Dentistry, PUSAN national university. The patient had natural tooth, the contralateral sides had implant-supported prostheses. The results were follows 1. The maximum bite force was little greater in implant-supported prostheses as 39.7kg than natural tooth as 36.8kg. This is because of the lack of periodontal ligament or inhibitory-reflex mechanism, higher maximal bite force could be expected when teeth are replaced by implants. 2. The maximal bite force is greater on implant-supported prostheses than natural tooth, but the masticatory function is higher at natural tooth. All of the patients who had implant-supported prostheses were comfortable during chewing the food. But, the masticatory function decrease because of psychologic problem and character of Korean food.