The chemical changes induced by electron-beam irradiation of mixtures of N-allylurea (AU) and amorphized starch were studied by spectroscopic methods for identifying and monitoring the reactions providing the blend with stabilized physical properties. Spectral modifications essentially concerned the AU constituent in the irradiated mixtures. FTIR and NMR analyses were used to quantify the progress of AU conversion upon irradiation and to gain information on the structure of the products. The influence of sample temperature and moisture on AU conversion rate was examined. The kinetic treatment of conversion vs dose data, from blends with different contents in AU, suggested that the phenomenological order for the reaction rate was zero. relative to the concentration in AU. The grafting yield was determined from combined H-1 NMR data recorded after selective solubilization of the constituents allowing for extraction of AU monomer and homopolymer from the grafted polysaccharide. Graft polymerization was more efficient than homopolymerization in samples containing AU in amounts less than its limiting solubility and relatively less efficient in thermodynamically unstable blends.