The prevalence of flat neoplasms in Western countries appears to be similar to Japan. These lesions are difficult to detect but careful examination of the colonic mucosa with the aid of targeted dye spray reveals subtle mucosal changes characteristic of these lesions. Management of flat neoplasms depends on their size, site and on whether the lesions lift after submucosal injection. In this article, we highlight the typical features of flat neoplasms and discuss their optimal management in routine practice.