The objective of the paper was to find a relation of the content of simple sugars in a potato tuber and its resistance to mechanical loads. The following potato tuber varieties were investigated: Kuras, Gala, Agata, Ditta, Arrow, Roko and Raja. A force damaging periderm, external and internal damages ratios and mass damages determined potato tubers susceptibility to mechanical damages. Measurement of the sugar content in the potato tubers was carried out with a refractometer. A statistically significant relation, measured with the value of the coefficient of correlation, between the content of simple sugars and susceptibility to internal damages was determined only in potato tubers of Kuras and Raja varieties.