Against a background of a rapidly aging society, the number of patients with oral cancers in Japan is increasing yearly. The number of double-cancers with oral cancer as the first malignancy is also reportedly on the rise. Esophageal and gastric cancers are the most common second malignancies. At our institution, our policy is to proactively perform upper gastrointestinal (GI) fiberscopy (GIF) in patients with oral cancer. In anticipation of a probable further increase in the number of patients with double-cancers consisting of oral and GI tract malignancies, we retrospectively analyzed the occurrence of upper GI tract cancers in patients with oral squamous cell carcinoma (OSCC). The cohort consisted of 171 patients in whom OSCC had been diagnosed and who had undergone upper GIF between March 1996 and August 2008. Multivariate analysis was performed. Upper GIF identified 8 patients (7 men, 1 woman, totaling 4.7% of 171 patients) with double-cancer in the upper GI tract. One patient had a triple malignancy consisting of oral, esophageal and gastric cancers. Seven patients had esophageal cancer, while two had gastric cancer. An age of over 65 years was significantly higher in patients with double-cancers including esophageal cancer than in patients without esophageal cancer (OR=10.454, 95% CI=1.143-95.621). None of the other analyzed patient factors (sex, smoking habit, drinking habit, site of OSCC, TNM classification, staging results) showed a significant difference. These results indicate that, when treating elderly patients with oral cancers, physicians need to devise suitable treatment plans which take into account the possibility of upper GI tract cancer, particularly esophageal cancer, as a double-cancer.