Abstract: A method for the production of a human recombinant lysosomal enzyme in a cereal plant endosperm, comprising: a first step of cereal plant transformation whereby the lysosomal enzyme is obtained and confined in an endosperm, which is not eventually absorbed by the embryo, and the presence of large quantities of the lysosomal enzyme in the endosperm does not negatively affect seed viability and germination speed; the use, in the first step of cereal plant transformation, of an endosperm-specific promoter upstream the gene encoding said lysosomal enzyme, and of a signal peptide for a co-translational transfer of the newly synthesized lysosomal enzyme into the lumen of the endoplasmic reticulum of the endosperm cells for its tissue-specific accumulation; a second step of lysosomal enzyme accumulation inside the seed endosperm of a cereal plant.