Abstract: A combined drilling and threading tool comprises a shank having a conical front portion defined by hole-cutting edges, and spirally curved ribs disposed rearwardly of the edges. A row of thread-cutting teeth is disposed along the leading edge of each rib. Each tooth includes a thread-cutting edge facing in the direction of tool rotation, and a side surface extending away from the direction of rotation. The side surface is shaped to produce axial and radial clearance relative to the thread being cut. Each tooth terminates at a location intermediate the leading and trailing edges of its associated rib.