The objective of this review was to determine whether consistent definitions were used in published studies of bloodstream infections due to central venous catheters in patients with cancer (ie, catheter-related or catheter-associated bloodstream infections). Review of 191 studies reporting catheter-related or catheter-associated bloodstream infections in patients with cancer revealed a lack of uniformity in these definitions. We grouped definitions by type, with 39 articles failing to cite or report a definition. Definitions included those of the Centers for Disease Control and Prevention (n = 39) and the Infectious Diseases Society of America (n = 18). The criteria included in the definitions in studies were also tabulated. Clinical manifestations were frequently included. Definitions used have been highly variable; comparability of risk factors, incidence, management, and outcomes of such infections is difficult to achieve across studies. Future research should focus on development of a common definition of catheter-related and catheter-associated bloodstream infections for both adults and children with cancer.