Three-year-long field and storage experiments were carried out to evaluate changes in concentrations of some organic acids in ‘Rywal’ and ‘Saturna’ potato tubers as affected by herbicides used during the growing period. The tubers were stored for 3 and 6 months at 4^oC and 8^oC at relative humidity of 95%. The weed control method did not change acid concentrations in the tubers. However, significant differences between the cultivars were seen. ‘Saturna’ had a higher content of citric, tartaric and fumaric acids, while that of malic acid was lower than in the ‘Rywal’ cultivar. There was a negative correlation between organic acids under study and malic acid after the harvest. The storage period and a lower storage temperature promoted accumulation of malic acid in both cultivars. A reverse relationship was noted in the case of other acids under study. The highest decrease, up to 70%, was found for fumaric acid assessed after 6 months of storage of the ‘Saturna’ cultivar.