Effective hemodialysis is not possible without efficient vascular access. Although arteriovenous fistula is widely recognized as the best of its kind, its formation in many cases is difficult or even not possible. Hemodialysis catheters are an essential part of renal replacement therapy. While these catheters are considered only the bridge to long-term vascular access such as arteriovenous fistulas or graft, they are associated with significant morbidity and mortality in hemodialysis patients. Although the proportion of patients with end-stage renal disease who have an arteriovenous fistula or arteriovenous graft pre-prepared is increasing, there are still many patients who begin hemodialysis using a hemodialysis catheter. In addition, the average age of patients receiving hemodialysis has recently increased, and accordingly, the number of patients with little life expectancy left, those who are very old, and who have difficulty in self-care is also increasing. In these patients, it is difficult to create vascular access, or even if it is created, there is a high possibility of maturation failure of access. Ultimately, a hemodialysis catheter is absolutely necessary for these patients. This lecture discusses the hemodialysis catheter and its necessity.