The invention relates to a roller vane pump suitable for pumping transmission fluid in an automatic transmission for motor vehicles. The pump is provided with a pump housing (2), a rotatable carrier (3) being located in the interior of the pump housing (2), a cam ring (5) surrounding the carrier (3) in radial direction, and roller elements (7) being provided in slots (6) in the carrier periphery. The spaces between the pump housing (2), the carrier (3), the cam ring (5) and the roller elements (7) define a number of pump chambers (8). Furthermore, the pump is provided with feed apertures (9) for allowing a flow of fluid to a pump chamber (8) and with discharge apertures (10) for allowing a flow of fluid from a pump chamber (8). According to the invention constructional measurements are taken to avoid the occurrence of cavitation and to obtain higher pump efficiency.