Abstract This paper presents a new method for 5-axis rough cutting of ruled surface pockets. An inclined zig-zag method is proposed for rough cutting the core material region, and an ellipse-offset method is developed for semi-roughing the residual material regions of ruled surface pockets. The ellipse-offset method is developed to calculate the non-constant offset curves for 5-axis tool path planning of rough cutting. Different from the traditional 21/2D machining method, the developed ellipse-offset method allows the cutter to change its tool orientation and to get as close to the part surface as possible in roughing. The proposed method allows the manufacturing engineers to use 5-axis machining to rough cut the parts to near-finish shape for finishing. Computer implementation and illustrative examples are presented in this paper.