Blends of thermoplastic starch (TPS) and zein were obtained by melt processing of cornstarch and zein, both plasticized with glycerol. DSC and X ray diffraction showed that starch crystallizes in a B-type structure and as V complexes. The presence of zein seems to have no influence in the type or amount of crystalline structure of starch. Zein reduces the water absorption of the blends and decreases their water diffusion coefficient, even at the lowest zein contents. Moreover, the processing of the blends is greatly facilitated by zein due to a strong reduction in their viscosity. These two favorable factors make zein a suitable and promising fully biodegradable component to be blended with starch.