血液透析（英语：Hemodialysis），是将血液抽出体外，经过血液透析机的渗透膜，清除血液中的新陈代谢废物和杂质后，再将已净化的血液输送回体内，俗称「洗肾」及「洗血」。

血液透析可用于肾衰竭病患，或血液中毒等身体无法自行排出毒害物质的情况。

采用血液透析的病患，每一周必须到医院接受2至3次治疗，洗血过程每次需时4至6小时，对于上班人士是一种困扰。至于采用腹膜透析者，可在家里进行，一个月回到医院1次即可。

延长透析时间可以减少血液透析的并发症、增加生活品质及降低死亡率，主要原因在于脱水速率较低及可以脱去更多的尿毒素；而最好的方法是利用每天晚上睡觉的时间进行血液透析，但是比起日间透析、更不会影响日常生活；只是要提供这样的服务，成本很高。

Hemodialysis, also spelled haemodialysis, commonly called kidney dialysis or simply dialysis, is a process of purifying the blood of a person whose kidneys are not working normally. This type of dialysis achieves the extracorporeal removal of waste products such as creatinine and urea and free water from the blood when the kidneys are in a state of renal failure. Hemodialysis is one of three renal replacement therapies (the other two being renal transplant and peritoneal dialysis). An alternative method for extracorporeal separation of blood components such as plasma or cells is apheresis.