A self-countersinking fastener for engagement with wood or similar composite material, said fastener including a penetrating shaft, and a tool engaging head; wherein said tool engaging head is substantially frusto-conical in overall shape and provided with one or more indent regions into which said material may be pushed as the head is turned; wherein each of said indent regions include: a trench extending substantially vertically through the entirety of said head; and a tailing section extending through the entire height of the head and extending forward in the direction of turning from said trench such that the radius of the head in the corresponding section increases throughout said section.