The number of haematopoietic stem cell transplantations (HSCT) in children has expanded in the last decades and still continues to increase. To ensure safe and effective care in this vulnerable high-risk population, treatment should be undertaken in a specialist unit by an experienced and fully dedicated multidisciplinary team. HSCT pharmacists are well-positioned to take a lead role in patient assessment and the development and implementation of guidelines for supportive care. This article aims to summarise the sparse literature data on clinical pharmacy activities in the paediatric HSCT setting augmented with advice from expert opinion. Many of these patients require routine management for immunosuppression or complications related to HSCT. Clinical activities for pharmacists include participation in ward rounds (where drug-related problems are discussed with physicians and nurses) and analysis of drug-related problems (eg, untreated indication, subtherapeutic or supratherapeutic dosages, non-conformity to hospital guidelines, therapeutic drug monitoring of immune suppressives or antibiotics, monitoring for drug-drug or drug-food interactions, detection of adverse reactions or problems with administration of intravenous drugs) and counselling on discharge medication. In addition, the pharmacist's role in the development and implementation of guidelines on acute effects or toxicities (mucositis, chemotherapy-induced nausea and vomiting, graft-vs-host disease, bacterial, viral and fungal infections) and late effects or toxicities (chronic graft-vshost disease) are discussed. BACKGROUND