A number of new European Medicines Agancy guidelines related to clinical investigation of medicinal products for the treatment and prophylaxis of venous thromboembolism (VTE) are already available [1,2,3], but recommendations are applicable only to adults. In contrast to adults, VTE in children is a rare event, but represents a significant management dilemma that requires therapeutic intervention. A paediatric addendum to the guidelines on clinical investigation of medicinal products for the treatment and prophylaxis of VTE is considered necessary to discuss and make methodological recommendations adapted to children.