**Abstract**

Expanded hemodialysis therapy is a new concept in blood purification technology using a specific membrane with a steep sieving curve characterized by medium membrane cutoff and high retention onset values that are close to but lower than those of albumin. Expanded hemodialysis therapy thereby targets an important pathophysiologic link to many of the sequelae of end-stage renal disease, by improving the clearance of medium to larger-size solutes. The significant internal filtration achieved in these hemodialyzers provides a remarkable convective clearance of medium to high solutes. This therapy does not need specific software or additional complex technology, making its application possible in every setting once the quality of the dialysis fluid is guaranteed to ensure the safe conduct of the dialysis session. The present chapter reviews the rationale for expanded hemodialysis therapy, the potential benefits, and the considerations for prescription and delivery.

**Keywords:** expanded hemodialysis, membrane cutoff, retention onset, internal filtration, medium molecular weight solutes
