Multiple primary cancers are not uncommon in the head and neck region. Since the time for treatment will be prolonged if each lesion is treated separately, simultaneous treatment of the cancers is preferred to ensure complete remission of lesions and increased survival of patients. In this paper, the efficacy of combined treatment was evaluated in 9 patients with oral cancers and concurrent cancers in other sites. The mean age of the patients was 54 years (range 44 to 66). The tongue (8) and mandible (1) were the sites of involvement. Concurrent cancers were found most often in the esophagus, followed by stomach and lung. Histologically, 7 lesions were diagnosed as squamous cell carcinomas. All oral cancers were treated by surgery. Neck dissection and simultaneous reconstruction were performed in 5 patients. In addition, concurrent cancers were treated simultaneously by endoscopic mucosal resection in 2 patients and radical resection followed by immediate reconstruction in 6 other patients. However, simultaneous surgical treatment of all lesions could not be performed in an individual with 3 cancers. The time of surgery ranged from 23 minutes to 17 hours and 30 minutes. With the exception of 2 patients who died of postoperative complications and had needed treatment for dysphasia, all patients were discharged after 1 to 2 months. Four of the patients are still alive 2 years and 6 months after surgery. These results indicate that simultaneous treatment is effective in selected cases of multiple cancers.