Abstract: An ejector pump has a ringshaped nozzle slot directed radially outwards followed by a radially directed mixing zone interacting with a secondary channel and a radially directed diffuser slot.To achieve an improved performance, and especially one having a characteristic less dependent to decreases of working medium pressure the ejector pump is comprised of two mutually fixed blocks (1, 2) having each an end surface (4, 6). Said end surfaces (4, 6) are facing each other forming an annular slot (12). The surfaces of the nozzle slot and the diffuser slot are profiled in at least one of said end surfaces (6) separated by an annular groove (7) in said end surface, which groove (7) communicates with the secondary channel. The diffuser slot height adjacent the groove (7) is larger than the nozzle slot height (h.sub.o) adjacent said groove decreasing outwardly by the way of at least two bevels, first one having an angle of bevel .alpha..sub.1 =8.degree.-15.degree. and then one having an angle of bevel=4.degree.-8.