An automatic tracking of the angular alignment position of mask with respect to the wafer in a photolithographic mask aligner is reported. It is demonstrated that automatic dynamic control with very high accuracy and stability of the angular alignment position is practically possible. The moire´ interference fringe method is employed for the present experiments. The alignment marks are used in the form of 25 &mgr;m pitch Ronchi ruling gratings. The best angular alignment accuracy obtained with the present experimental conditions is of the order of 2×10−7rad. An alignment accuracy up to ±3×10−7rad is reported for more than 30 min which enables the present technique to be used for the real photolithographic mask aligner. ©1995 American Institute of Physics.