A pump comprises a housing (10, 210, 300, 410), the housing having an interior defining a rotor path (10, 210, 300, 410), an inlet (111, 211) formed in the housing (10, 210, 300, 410) at a first position on said rotor path, an outlet (12, 212) formed in the housing (10, 210, 300, 410) at a second position on said rotor path spaced from said first position. A rotor (15, 315, 350, 415) is rotatable in the housing. At least one first surface is formed on the rotor (15, 315, 350, 415) and seals against said rotor path of the housing (10, 210, 300, 410). At least one second surface is formed on said rotor (15, 315, 350, 415) circumferentially spaced from said first surface and forms a chamber with the rotor path that travels around said rotor path on rotation of the rotor (15, 315 350, 415) to convey fluid around the housing (10, 210, 300, 410) from the inlet (111, 211) to the outlet (12, 212). A resilient seal (114, 214) is formed in one piece with the housing (10, 210, 300, 410), located on said rotor path and so extends between the outlet (12, 212) and the inlet (111, 211) in the direction of rotation of said rotor (15, 315, 350, 415) that the first rotor surface seals with, and resiliently deforms, the seal (114, 214), as the rotor (15, 315, 350, 415) rotates around the rotor path within the housing to prevent fluid flow from said outlet (12, 212) to said inlet (111, 211) past the seal. A passage (101, 201) may be provided to supply fluid to an under surface of the seal (114, 214) at a pressure that acts to urge the seal (114, 214) against the rotor (15, 315, 350, 415). The rotor path may be frustoconical with the first surface of the rotor (15, 315, 350, 415) also being frustoconical and being a mating fit with the rotor path.