A fuel injector for an internal combustion engine comprising a nozzle body having at least one spray hole. The at least one spray hole has a hole entry on the inside of the nozzle body and a hole exit on the outside of the nozzle body. The spray hole is provided with a hole entry section which, starting from the hole entry, has a flow area which decreases from a relatively larger flow area at the hole entry to a relatively small flow area at the intersection between the end of the hole entry section and the start of a hole exit section. The hole exit section, starting from the intersection with the hole entry section, has a flow area which increases from a relatively small flow area at the intersection with the hole entry section to a relatively larger flow area at the hole exit.