Radial distribution functions of the microcrystalline particles in fibers are derived from the x‐ray scattering at small angles. Particle distribution functions are obtained by application of the method of Fourier synthesis to the x‐ray data, by inversion of the intensity scattered under conditions where interparticle interference plays a part.Different distribution curves are obtained with different fibers, investigated under the same conditions.The distribution curves obtained with the same fiber investigated under different conditions of swelling, are consistent with the wider separation of the particles at higher degrees of swelling. A quantitative explanation is thus given of the differences between the scattered intensities at different degrees of swelling.The degree of crystallinity is calculated from the distribution curves, so obtained, in combination with the particle sizes determined in preceding papers.