The use of peripherally inserted central catheters (PICCs) represents a major advance for hematological patients, enabling the effective delivery of chemotherapy and/or blood products particularly for prolonged infusions or in situation of difficult venous access. In modern medical practice their use has increased rapidly for several reasons, including ease of insertion, many uses (e.g., drug administration and venous access), perceived safety, and cost-effectiveness compared with other central venous catheters (CVCs). Despite these benefits, PICCs are associated with deep vein thrombosis of the arm and pulmonary embolism. These complications, which are often called venous thromboembolism, are important because they not only complicate and interrupt treatment, but also increase cost, morbidity and mortality. Despite this effect, the burden and risk of PICC-related venous thromboembolism is uncertain and clinicians have scarce evidence on which to base choice of vascular access. Evidence to choose one vascular access over the other is lacking in literature, in particular for patients affected by haematological malignancies, in which chemotherapy is more likely to cause myelosuppression, with a major risk of bloodstream infections. Furthermore, the precise incidence and the risk of PICC-related venous thromboembolism relative to that of other CVCs is unknown. An understanding of this risk in the context of growing PICC use is an important cost and patients safety questions. Up to now, no systematic review has been done to investigate these questions.