In many jurisdictions, cost-effectiveness analysis (CEA) plays an important role in determining drug coverage and reimbursement and, therefore, has the potential to impact patient access. Health economic guidelines recommend the inclusion of future costs related to the intervention of interest within CEAs but provide little guidance regarding the definition of 'related'. In the case of CEAs of therapies that extend the lives of patients with chronic kidney disease (CKD) on dialysis but do not impact the need for or the intensity of dialysis, the determination of the relatedness of future dialysis costs to the therapy of interest is particularly ambiguous. The uncertainty as to whether dialysis costs are related or unrelated in these circumstances has led to inconsistencies in the conduct of CEAs for such products, with dialysis costs included in some analyses while excluded in others. Due to the magnitude of the cost of dialysis, whether or not dialysis costs are included in CEAs of such therapies has substantial implications for the results of such analyses, often meaning the difference between a therapy being deemed cost effective (in instances where dialysis costs are excluded) or not cost effective (in instances where dialysis costs are included). This paper explores the issues and implications surrounding the inclusion of dialysis costs in CEAs of therapies that extend the lives of dialysis patients but do not impact the need for dialysis. Relevant case studies clearly demonstrate that, regardless of the clinical benefits of a life-extending intervention for dialysis patients, and due to the high cost of dialysis, the inclusion of dialysis costs in the analysis essentially eliminates the possibility of obtaining a favourable cost-effectiveness ratio. This raises the significant risk that dialysis patients may be denied access to interventions that are cost effective in other populations due solely to the high background cost of dialysis itself. Finally, the paper presents a case for excluding dialysis costs in CEAs of therapies that extend the lives of patients receiving dialysis but do not impact the need for dialysis. The argument is founded on the following: (i) health economic guidelines imply that dialysis costs are unrelated to such therapies and therefore should not be included in CEAs of such therapies; (ii) the high cost and cost-effectiveness ratio associated with dialysis place an unreasonable and insurmountable barrier to demonstrating the cost effectiveness of such therapies, particularly since the decision to fund dialysis has already been made; and (iii) current clinical and reimbursement practices include the use of such therapies for patients with CKD receiving dialysis. We conclude that the exclusion of dialysis costs in such cases is methodologically correct given current health economic guidelines and is consistent with current practices regarding the treatment of dialysis patients.