New paleomagnetic data from middle Eocene to middle Miocene volcanic and plutonic formations of the Western Cordillera of Central Peru document a counterclockwise rotation of 11°±7.4°. This rotation, similar to previous results reported for the northern Peruvian margin, is post middle‐Miocene in age. It is thus coeval with the acceleration of the Andean uplift and supports Isacks' model. Copyright 1992 by the American Geophysical Union.