An internal combustion engine fuel injector having a selectively openable nozzle (10) through which fuel is delivered to a combustion chamber of the engine. The nozzle (10) comprises a port (12) having an internal annular surface (13) and a valve member (20) having an external annular surface co-axial with respect to the internal annular surface. The annular surfaces being shaped so that when the internal and external annular surfaces are in sealing contact closing the nozzle the maximum width (17) of the passage between the said surfaces is not substantially more than 40 microns, preferably not more than 20 microns, in the direction normal to said surfaces.
