Portable or wearable dialysis devices could increase treatment flexibility and dialysis patients' independence. Current renal replacement therapies such as intermittent haemodialysis extend life but are a burden, are time-consuming and immobilize patients. An additional disadvantage is the discontinuous nature of the treatment. Peritoneal dialysis is a good alternative, but is associated with relatively limited toxin clearance and a need for high glucose concentrations in the dialysate. Portable dialysis devices could be used as a replacement or to support existing dialysis techniques. At the moment several initiatives, including some started in the Netherlands, aim at the development of a portable device. Some of them are so far into development that they are at a preclinical phase, but as yet none has been approved for regular use in patients. To achieve the ultimate goal, an implantable artificial kidney, a lot of hurdles still have to be surmounted.