In medical applications, anisotropic volume data sets are commonly used, of which the resolution in an axial plane is higher than that in the direction perpendicular to it. In this paper, we propose an efficient anisotropic volume rendering method based on intensity interpolation that obtains the intensity value at an interpolated position lying between voxels in two consecutive slices from the intensity values of the voxels. Unlike density interpolation method, it does not require long preprocessing time and extra memory for storing the interpolated slices. Experimental results show that this method improves rendering speed without significantly sacrificing image quality.