The role of the nurse in infusion therapy has evolved with advances in vascular access technology and the variety of infusion devices available. With increasing numbers of patients requiring vascular access for a range of parenteral therapies, nursing staff need to demonstrate an understanding of the range and management of vascular access devices (VADs) and the clinical indications for individual devices. This article, the first of two, provides information on the type of VADs available and emphasises the importance of patient assessment to ensure safe, reliable and high-quality care for individual patients. The second part, to be published next week, examines some of the common complications associated with infusion therapy and identifies preventive measures.