Small angle x‐ray scattering data have been obtained for concentrated suspensions of southern bean mosaic virus containing approximately 20, 10, and 5 gm virus per 100 ml of suspension. In addition, the scattering from independent virus particles was determined from the scattering curves for dilute suspensions. The Zernike‐Prins equation was used to compute the pair correlation functions for the concentrated suspensions. The pair correlation functions indicated relatively weak interparticle forces. The effective distance of closest approach of two particles was appreciably greater than the particle diameter, which was approximatley 285 Å. The interaction potential energy for a pair of molecules was estimated by three different approximate theories.