We investigate the existence of anisotropy near the top of the inner core under the western hemisphere using differential travel times of pole-parallel PKPcd-PKPdf phase pairs and comparisons to equatorial data. We invert a large dataset of PKP differential travel-time residuals in the same region for a layered model of inner core anisotropy. Our analysis shows that the uppermost 50--150 km of the inner core in this region is isotropic. This implies that anisotropy at greater depths is higher than previous estimates, perhaps as high as 5%. The transition from isotropy to strong anisotropy is modeled as a discontinuity, but a broad transition zone is not excluded by the data. We offer several possible mechanisms for the existence of a layered structure of anisotropy. ¿ 2001 American Geophysical Union