Abstract: Disclosed is an infusion pump for expelling a fluid from a collapsible fluid reservoir to a patient. The pump includes a housing having a chamber therein for receiving the fluid reservoir. A first wall is provided on the housing for contacting the fluid reservoir, and a second wall is movable from a first position distanced from the first wall to form the chamber therebetween, and a second position relatively closer to the first wall. Advancing the movable wall from the first position to the second position expels fluid from the collapsible reservoir at a substantially constant rate by applying increasing force on the fluid reservoir through the dispensation cycle. Preferably, the first and second walls are provided with non-planar complementary surface configurations for contacting the collapsible reservoir. Retraction mechanisms for retracting the movable wall from the second position to the first position, and user readable indicium of the status of the dispensation cycle are also disclosed.