The study shows that density decrease modification of peeled potato tubers results from water absorbance. The research was conducted after an eight-month period of storage during the 2004/05 storing season. The research was applied to three tuber size fractions of four potato varieties. The research shows that the statistical density decrease was influenced significantly by all the parameters adopted in the research, i.e. absorbance time, potato variety, and tuber size fraction. The density decrease, after 3.5 h of water absorbance, equals around |–13·10-3| g cm-3. The density decrease grew along with tuber size reduction. Along with water absorbance, the density decrease increased, and the resultant changes were formulated by means of logarithmic functions.