This comprehensive handbook provides an essential source of information and practical advice for medical students, trainee and pediatric residents. Although the development of information via the internet has made it easy to learn, find information and communications, yet this handbook has collected most of the essential information needed about gastrointestinal disorder during childhood. As in most of my handbook, this book also starts with congenital malformation of the gastrointestinal tract. Problems that arise from the congenital malformation present very early in infancy as surgical emergency situation that threaten lives if not managed promptly. An important chapter in this handbook is the Functional Gastro-intestinal disorder of infancy. These are very common problems affecting about half the population of infant across the globe. They comprise a range of recurrent disorders that are explained by anatomical, structural or biochemical abnormalities. Acquired gastrointestinal disorders are mentioned in details so as the inflammatory bowel diseases. Vomiting is a major symptoms in children of all age groups and so I have chaptered it separately in this handbook. Diarrhea is one of the most common illness among children in developing countries with 1.5 billion episodes of diarrhea and 4 million associated deaths among children each year. This is why it is important to be familiar with its causes of which foods poisoning is part of and method of treatment. Malabsoption Syndrome are disorders affecting the digestion and absorption of nutrients key to survival. Key to dehydration management is prevention of dehydration and promotion of rehydration in those already dehydrated. Failure in management is the major cause of morbidity and mortality in gastro enteritis cases. Accurate diagnosis of defecation disorders impacts treatment outcomes. This can be achieved through the accurate recording of key information gathered from history, examinations, discussion with patients about family history and dietary habits. Liver disease developments is silent with no signs or symptoms and one of the leading causes of premature death in England responsible for more than 1 in 10 deaths of people in their 40's. This book is a summation of the knowledge culminated from 40 + experience in the specialty as a consultant pediatricians and a fundamental reference to people passionate about medicine.