There is disclosed a low-cost, axial fluid pump which does not involve the conversion of rotary to linear motion. The fluid pump herein is based on the principle of successively using a ball, that may be obtained from a reservoir of similar balls, as a piston within an enclosed cylinder. The ball is made to traverse the cylinder's length by simple non-motor means, thereby compressing the fluid. Upon pressurizing the fluid, the ball eventually returns to the reservoir and a new ball from the reservoir repeats the compression cycle. The pump of this invention is adapted for low pressure, low rate of flow, and low cost applications.