Abstract: Tennis rackets having racket strings which are not round. The strings are provided with a cross-section of a geometrical shape such as to provide each string with two or more edges. The strings are also provided with a helical twist along their length during their formation by extrusion; they are also provided with approximately one-half of a helical twist per unit of length corresponding to the distance between adjacent cross-over points of the strings and at such points there is surface to surface rather than edge to edge engagement.