Starches isolated from two potato varieties (Udacha, Acrosil) at different stages of maturation were investigated using X-ray diffraction and high sensitivity differential scanning microcalorimetry methods. Applying some physico-chemical approaches, the thickness of the crystalline lamellae and the thermodynamic parameters characterizing their surface faces were determined. The thickness of crystalline lamellae is practically equal to the corresponding value in an amylopectin model proposed by Robin et al. The values of the thermodynamic parameters for the face sides of the starch crystalline lamellae are one order of magnitude smaller than the corresponding values for polyethylene crystals. Some concepts concerning structural changes during biosynthesis if starch potato granules are discussed.