Poly(lactic acid) (PLA) is one of the most promising and ready to market material for applications in packaging. A right balancing of stiffness and impact resistance is however necessary for its properties modulation in both flexible and rigid items. The use of additives, also in combination, or the blending with other thermoplastic polymers gives the opportunity of controlling both processability and final properties of PLA based blends and compounds. Other biodegradable polyesters such as proteins, much affected by thermal degradation during processing, not yet developed on a large industrial scale, can offer opportunities for processing natural polymers coming from food or agro-waste. The advantage of this approach is the possibility of adopting traditional extruders for processing such blends, even if the modification of the process and the development of new technologies is often necessary. In the latter case, although this topic is still at an early stage of development, it seems evident that it is necessary the control of melt viscosity and compatibility to develop biodegradable blends with controlled and reliable properties. Keywords: polyesters, poly(lactic acid), biodegradable, renewable, proteins