The Danish parliament has decided to establish a four-year pilot scheme for medical treatment with cannabis. We increasingly experience requests from parents for medical treatment with cannabis of children and have the impression that a growing number of parents treat their children with illegally acquired cannabis products for various conditions. We summarize the sparse evidence regarding effects, side effects and long-term effects of medical treatment with cannabis in children and adolescents. At present, cannabis should very rarely be considered as part of medical treatment for children and adolescents.