The increasing incidence of multiple primary carcinomas occuring in the upper aerodigestive tract is well documented, with the accepted incidence being as high as 20-30%. The fiberoptic endoscopy has also enabled visualization of areas previously inaccessible without general anesthesia. A prospective panendoscopic examination of the upper aerodigestive tract was peformed on 104 patients with squamous cell carcinoma of head & neck in our hospital between 1989 and 1994. Five second primary cancers (4.8% ：2 stomach, 2 esophagus, 1 lung cancers) were detected endoscopically. These finding should reinforce the belief that head & neck cancer is a panmucosal disease of the aerodigestive tract that silent second primary cancers are not uncommon. So every effort should be done to detect second primary cancers in head & neck squamous cell carcinomas. Panendoscopy has proved valuable in achieving that.