Quantitative grazing-incidence small-angle x-ray scattering experiments have been performed on self-assembled InAs quantum dots (QDs) grown by molecular-beam epitaxy. We find pronounced nonspecular diffuse scattering satellite peaks with high diffraction orders, indicating a lateral ordering in the spatial positions of the InAs QDs. The mean-dot–dot distance and correlation lengths of the dot lateral distribution are found to be anisotropic. We observe the sharpest dot distribution in the [110] direction. Additional broad diffraction peaks are observed and associated with dot facet crystal truncation rods of the {111} and {101} facet families. This suggests an octagonal-based dot shape.