Melting point depression techniques are used to test the compatibilty of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The novelty of the experimental approach lies in the morphology of the melting lamellae, which is kept constant by using identical single crystals in various mixtures with PMMA. The values obtained for the Flory-Huggins interaction parameter are critically compared with those existing in the literature. Besides that, the effect of PMMA upon the kinetics of melting of PVDF is described.