Abstract: A tube assembly for a peristaltic pumping system is described. The assembly includes resilient inner and outer tubes of which the inner tube has a lumen along which liquid can be pumped by occluding the tube and causing the point of occlusion to progress along a length of the tube defining a pumping zone. The outer tube fits closely around the inner tube and extends over said zone. The tubes are free of attachment to one another over at least a substantial part of said zone so that the contacting surfaces of the respective tubes define an interface along which relative movement between the tubes can occur during pumping. The tubes are secured together at at least one point along their lengths. It has been found that abrasion of the innermost surfaces of the inner tube is minimized and that reduced contamination of the liquid being pumped and increased pump tube life can be expected as compared with conventional peristaltic pump tubes.