Abstract: The present invention relates to a method and an apparatus for calibration of an industrial robot system including at least one robot (1) having a robot coordinate system (xr1,yr1,zr1) and a positioner (2) having a positioner coordinate system (xp,yp,zp) and adapted to hold and change the orientation of a workpiece by rotating it about a rotational axis. Target points for the robot are programmed with respect to an object coordinate system (xo1,yo1,zo1). The apparatus comprising a robot controller (3), at least three calibration objects (24a-c) arranged on the positioner, and a calibration tool (26) held by the robot. The positions of the calibration objects are known in the object coordinate system.