A peristaltic pump having a plurality of removable cartridges, each containing a length of tubing, and each having means for adjusting occlusion comprising a linearly displaceable occlusion bed. Tubing retainers on each cartridge stabilize the tubing segments to constrain them against longitudinal displacement during pumping. Means are provided to enable visual determination of occlusion adjustment through the top of each cartridge. Each of the cartridges is reversible, and is readily installed on the pump frame and retained thereon by a snap-lock mechanism.