Patient non-adherence is a pertinent issue as it induces adverse disease outcomes, poor prognosis, and diminished quality of life. Concerns for non-adherence are further pronounced in End-Stage Kidney Disease (ESKD) patients as treatment is highly complex and demanding with dialysis sessions, multiple medications, and lifestyle restrictions related to dietary and fluid management. Summarising literature on adherence in dialysis patients, this chapter starts by introducing the treatment rationale and regime for ESKD patients undergoing dialysis, followed by a delineation of relevant measures and criteria related to, and rates of non-adherence. An assortment of methods is being used to assess adherence rates in dialysis patients, among which the examining of biochemical markers and patient self-report are the most prevalent. Rates of non-adherence in dialysis patients warrant urgent attention as they can be as high as 18% for missed dialysis sessions, 22.4% for shortened treatment time, 80.4% for medication, 75.3% for fluid restrictions and 81.4% for dietary restrictions. There is a disproportionate emphasis on haemodialysis over peritoneal patients. Paramount to drive efforts to improve treatment adherence in this patient population, demographic, clinical and psychosocial determinants of non-adherence are also highlighted. This chapter concludes with a brief overview on educational and psycho-educational interventions used to improve treatment adherence in patients undergoing dialysis.