Small-angle X-ray scattering (SAXS) is a structural characterization method applicable to biological macromolecules in solution. The great advantage of solution scattering is that the systems can be investigated in near-physiological conditions and their response to external changes can also be easily investigated. In this chapter, we discuss the application of SAXS for studying the conformation of helicases alone and in complex with other biological macromolecules. The DEAD-box helicase eIF4A and the DEAH/RHA helicase Prp43 are investigated for their solution structures, and the analysis of the collected scattering data is presented. A wide range of methods for analysis of SAXS data are presented and discussed. Ab initio methods can be used to yield low-resolution solution structures, and when models with atomic resolution are available, these can be included to aid the determination of solution structures. Using such prior information relating to the systems studied and applying a variety of methods, substantial insight can be gained about solution structures and interactions of biological macromolecules through small-angle scattering.