Commercially, gelatin is a heterogeneous proteinaceous product with a broad range of molecular weights. The use of gelatin to prepare insoluble nanoparticles depends very largely on the presence of high molecular weight fractions which can be separated by size exclusion chromatography. The purpose of this study was to determine the molecular fractions of gelatins from three commercial types (B225, B60 and A60), measure their molecular weights and compare these data with those obtained from an absolute light scattering method. The mean molecular weights of the gelatins decreased in the order: MB225 > MB60 > MA60. All the samples were polydisperse, with fractions varying from <50 kDa to >2MDa. Arbitrarily, each sample was divided into eight fractions based on the molecular weight distribution and using a paired t-test the two methods were shown to be in substantial agreement. The light scattering method would appear to provide an absolute quality control procedure for commercial gelatin, depending on its application and requirements.