Abstract The glycogen storage diseases (GSDs) are a large group of disorders that present in a variety of ways to paediatricians. Some of them primarily have problems with hepatic glucose production and its secondary consequences: hypoglycaemia, lactic acidosis, hepatomegaly (e.g. GSD I). Others mainly cause problems with muscle metabolism and function (e.g. GSD V). Some have a combination of both liver and muscle involvement (e.g. GSD III). This review focuses on these three disorders (types I, III and V), to emphasize the differences between them, the differences within them and their multi-system natures. The clinical features, diagnostic investigations and therapeutic interventions will be discussed. Increasing numbers of children with these disorders are now surviving into adulthood and developing a number of long-term complications. These need to be screened for and managed appropriately. Although treatment is better now than in the past, further improvements are still required to enhance the quality of patients' and families' lives, as well as to reduce the incidence of complications in later life.