A thread cutting tap having a threaded portion for cutting out a thread in a wall of a workpiece opening into which the threaded portion is to be introduced. The threaded portion is provided with at least two cutting edges extending in a circumferential direction of the body. Each cutting edge is an integral peripheral part of a flank portion extending substantially radially from the body. The flank portions define between one another a chip removal flute extending in the longitudinal extension of the body for removal of chips. At least one of the flank portions has a side wall divided into a pair of elongated concave surfaces separated by an elongated ridge constituting a chip-breaking member. The chip removal flutes are at least partly helically shaped.