New sizing agents from natural origin were obtained by reaction between maleic anhydride and esters from vegetable oils and mainly alkyl oleates. They belong to the alkenyl succinic anhydrides family (ASA). Paper hydrophobation, which limits water penetration, relies upon the reaction between the hydroxyl fonctions of cellulose and the anhydride moiety of ASA. Our vegetable ASA (oleo-ASA) are characterized by a maximum composition in C18:1 and a varying terminal ester moiety. More than thirty oleo-ASA were tested as paper sizing agents at laboratory scale. Among them, three oleo-ASA presented a sizing and an emulsion behaviour equivalent to the one obtained with petrochemical ASA, commonly used in industry. Moreover, their hydrolysis in diacid is two-fold slower and their resistance to stripping phenomenon is ten-fold higher. Their use would then allow longer emulsion storage and fewer deposits in air ducts. These advantages make them excellent candidates to the substitution of ASA from fossil origin. Once the synthesis and purification of the three preceding molecules optimized, one among them has been successfully tested as sizing agent at a 100 kg paper machine pilot scale.