The morphology, crystallization behavior and mechanical properties of PLA, PHBV and their blends and nanocomposites with TiO2 as filler were investigated. An uncommon morphological change was observed with increasing PLA content in the blends, and this complicated the isothermal crystallization kinetics analyses of the different samples. It was, for example, observed that PLA, which do not normally crystallize during the cooling of the sample, showed isothermal crystallization for certain blend compositions. TiO2 was found to be mainly present in the PLA phase, which was also confirmed through broadband dielectric analysis. The blend composition, as well as the presence of TiO2 nanoparticles, had an influence on the cold crystallization of the PLA. The tensile properties changed with blend and nanocomposite composition, and these changes could to a certain extent be related to the respective morphologies. Very little could be said about differences between the melting behavior of the different samples, because the PLA and PHBV melted at almost exactly the same temperature.