The accuracy of tooth profiles of gears finished by form grinding is strongly affected by positioning errors between the grinding wheel and the work gear, such as errors in the center distance, the inclination angle of the wheel axis and the position of the grinding wheel in the axial direction. In this paper, the effects of these positioning errors on the profile errors of the helical gears being ground are investigated numerically and two practical methods to compensate the profile errors of the gears ground with the positioning errors are proposed. One is a method of modifying the grinding-wheel profile based on the measured profile error of the ground gear. The other is a method of analyzing interactively and removing the positioning errors producing the profile error of the ground gear. To demonstrate the usefulness of the methods, error compensation for the involute helical gear ground with two or more kinds of positioning errors is conducted.