Abstract: A method of assembling a peristaltic pump having a motor housing having a driveshaft extending therefrom and a pump housing containing a pump including a rotor mounted on a stub shaft extending through the pump housing wherein the motor housing and the pump housing are detachably connected together. They are assembled by positioning the motor housing and the pump housing so as to axially align the stub shaft and the driveshaft, and moving the pump housing towards the motor housing in the axial direction of the driveshaft so that the driveshaft enters the pump housing and engages the rotor while the stub shaft is urged axially out of the pump housing. When the pump housing contains two or more rotors the stub shaft preserves the alignment of the rotors both during manufacture of the pump assembly and transportation of the pump housing.