In recent years, the development of biodegradable polymer materials and/or obtained from renewable sources has become a major focus of research in the packaging and biomedical areas. In this context, it has to be highlighted the use of poly(lactic acid), PLA, a biodegradable and biocompatible thermoplastic obtained from renewable sources and with similar properties when compared with petroleum-based polymers. One of the main disadvantages of this polymer is its inherent brittleness. Thermoplastic polyurethanes (TPUs) are excellent candidates for toughening agents in PLA blends as they exhibit a combination of high elasticity and ductility with biocompatibility and biodegradability. In this study, uncompatibilized blends of PLA/TPU (PLA/TPU ratios of 100/0, 75/25 and 50/50) were produced by melt mixing and their thermal, rheological and mechanical properties (tensile and notched Izod impact) were evaluated. DSC results suggested that the blends were immiscible and that the presence of TPU had little influence on the PLA’s crystallization behavior. Rheological measurements showed an increase in elasticity and viscosity at low shear rates with the addition of TPU but also an increase in the shear thinning behavior, which suggests a minor impact on the processability. Regarding the tensile mechanical behavior, it was observed a decrease in the elastic modulus and an increase in the elongation at break as higher the TPU content, as expected. The results of impact resistance should be emphasized: even without compatibilization, considerable increases were observed, confirming the potential of TPU as a toughening agent for PLA.