Transformation of potato cultivar (Desiree) has been achieved using different types of explant tissue (minituber, stem and leaf discs) via infection with an Agrobacterium tumefaciens harboring a kanamycin resistance gene. The product of it, an aminoglycoside phosphotransferase, has been determined in the protein extracts of the transformants in addition to the common rooting tests. Certain influences of the type of the explants upon the transformation efficiency and the morphology of the regenerated transgenic plantlets have been noticed. A selection and regeneration protocol for the potato transformants is described. A periodical study of the foreign gene stability and reversibility tests with demethylating agent of the relevant lines have been performed. A possible involvement of DNA methylation processes in the variable transgene expression in potato plantlets is discussed.