Oxide dispersion-strengthened steels are among the most promising materials for Generation IV reactor installations and thermonuclear power generation due to their high heat resistance, which is achieved by a significant number of uniformly distributed oxide particles. These materials can withstand temperatures up to 700°C and mitigate radiation-induced swelling within 200 dpa. The enhanced properties of such steels significantly depend on the specifics of their nanostructure, namely, the size and spatial distribution of dispersive inclusions (oxide particles and clusters). In this study, small-angle neutron scattering is applied to characterize the nanostructure of oxide dispersion-strengthened steels. This method enables the analysis of a large volume of material while retaining the ability to detect features such as clusters with sizes in the range of a few nanometers. The investigated steels have different alloying systems, varying in their concentration of Cr, V, W, Al, and Zr. Small-angle neutron scattering enables determination of the characteristic sizes of nanoscale inclusions in oxide dispersion-strengthened steels and their number densities. The results of smallangle neutron scattering are compared to the findings of transmission electron microscopy and atom-probe tomography.