High-resolution X-ray diffraction studies of the perfection of state-of-the-art multilayers are presented. Data were obtained using a triple-axis perfect-crystal X-ray diffractometer. Measurements reveal large-scale figure errors in the substrate. A high-resolution triple-axis set up is required, therefore, to obtain structural information about the layers. Measurements of reflectivity from parallel layers are presented as well as measurements of the angular distribution of the layer normal over the illuminated spot. These measurements are supplemented with measurements of scattering obtained in the total external reflection regime.