In most disorders of the gastrointestinal mucosa that occur in children and adults, the mucosal manifestations are the same. This article focuses on disorders and approaches to gastrointestinal procedures and mucosal biopsy that are of a particularly or peculiarly pediatric nature. This article discusses, in detail, the issues pertaining to endoscopy and other techniques of mucosal biopsy in children. Some approaches and techniques are considerably different than those in adults.