For many chronic conditions, poor patient compliance with prescribed medications and other aspects of medical treatment can adversely affect the treatment outcome. Compliance with long-term treatment for chronic asymptomatic conditions such as hypertension is on the order of 50%. Although drugs with a longer therapeutic half-life may ease the burden of repeated daily dosing, the efficacy of any self-administered medication depends to a large extent on patient compliance. This article addresses the compliance issues in patients undergoing renal replacement therapy and in those with a successful renal transplant. A focused discussion of compliance in dialysis and renal transplant patients is followed by a general review of the literature on patient compliance. Many factors associated with poor compliance in this patient population are identified via a review of the recent literature. The difficulties in monitoring medication compliance and the methods used are discussed. Among factors associated with poor compliance, the following have been identified in several studies: frequent dosing, patient's perception of treatment benefits, poor patient-physician communication, lack of motivation, poor socioeconomic background, lack of family and social support, and younger age. Many strategies have been suggested to improve medication compliance, most without scientific validation. Strategies to improve compliance in dialysis and transplant patients are similar to those described for other chronic conditions and include simplifying the treatment regimen, establishing a partnership with the patient, and increasing awareness through education and feedback.