Adherence to fluid restrictions and dietary and medication guidelines as well as attendance at prescribed hemodialysis sessions of a hemodialysis regimen are essential for adequate management of end-stage renal disease. A literature review was conducted to determine the prevalence and consequences of nonadherence to the different aspects of a hemodialysis regimen and the methodological obstacles in research on nonadherence. Nonadherence to the prescribed regimen is a common problem in hemodialysis and is associated with increased morbidity and mortality. Research on nonadherence is associated with 2 major obstacles: inconsistencies in definitions and invalid measurement methods. Further research is needed to validate measurement methods and to establish clinically relevant operational definitions of nonadherence.