Abstract: The invention is directed to a pump for use as a lubricating oil pump in internal combustion engines of handheld portable tools such as motor-driven chain saws or the like. The pump includes a body forming the stator and a body forming the rotor. These bodies lie coaxial with respect to each other and have respective surfaces which lie seal-tight against each other. A screw-shaped spiral slot is formed in one of these surfaces and has an input end connected to a suction connection and an output end connected with a pressure connection. According to a feature of the invention, at least the screw-shaped wall structure is made of an elastomer. This wall structure defines the spiral slot and lies against the smooth surface lying opposite thereto. An absolutely seal-tight contact engagement of the wall structure defining the spiral slot against the opposite-lying surface is assured by the elasticity of the elastomer. The service life of the pump is increased and its production and assembly simplified.