Abstract: This invention relates to a grease pump and in particular to one including a body portion having a main tube and a cover threadedly engaged with an end of the main tube, an adjusting device mounted with the main tube and having a throttle valve, a steel ball, a seat, a first piston, and a first Venturi tube, a resilient member disposed within the first Venturi tube, a pumping device including a second Venturi tube, a sleeve, a second piston, two oil seals, a head, a packing and a nozzle, a sealing ring mounted between the nozzle and the head, whereby the grease pump may be operated with a single hand and is especially useful in a narrow space.