The effects of genotype, climatic conditions during storage period on the contents of dry matter, reducing and total sugars, enzymatic and after cooking darkening, processing quality and the fitness of new registered potato cultivars in Poland were examinated. Dry matter content depended mostly on the genotype. The storage temperature and time increased dry matter content. Reducing sugars content depended on the cultivar, but the storage temperature affected the reducing sugar content and colour of fried product. The tubers of Felka Bona, Pirol, Nora, Redstar and Monsun cultivars can be stored at 4°C (4°C type - cold storage), because their reconditioning successfully decreased the content of reducing sugars. Total sugar contents in potato tubers increased especially after 7 month storage at both (4° and 8°C) storage temperature. The Andromeda, Clarissa, Ditta, Satina, Vitara, Żagiel, Korona, Krasa and Molli cultivars showed high content of total sugars (>1%) after storage at 4°C. Intensity of darkening depended on the cultivar and time of storage. Gracja, Innovator, Kuklik, Karatop cultivars were susceptible to after cooking darkening while the Gracja, Krasa, Korona, Asterix, Pirol, Velox, Romula, Zeus, Molli i Felka Bona cultivars to enzymatic browning.