Abstract. In this paper, we show that combining Multiwavelength Anomalous Diffraction (MAD) and Diffraction Anomalous Fine Structure (DAFS) spectroscopy, in grazing incidence geometry, allows to obtain structural properties (strain and composition) of semiconductor nanostructures. We report results obtained on dome-shaped Ge nano-islands grown on Si(001) surfaces and AlGaN nanowires grown on Si(100). It is shown that, in the case of sharp interfaces, MAD alone can not determine the mean Ge content in the region of the substrate-island interface and needs to be combined with Extented-DAFS measurements.