The study was based on the results obtained from three field experiments on sprinkler irrigation of three medium-early potato cultivars (‘Dorota’, ‘Gracja’ and ‘Orlik’) conducted in the years 2005-2007. The aim of the study was the estimation of needs and results of sprinkler irrigation for medium-early potato crop grown on very light soil in the vicinity of Bydgoszcz, the region of the lowest rainfall during the vegetation period. Water needs of potato estimated according to Press were higher than those calculated according to Klatt. Yields of non-irrigated potato were dependent on the rainfall amount during the vegetation period. The yields increased from 9.18 t ha-1 (rainfall VI-VIII 90 mm) to 21.2 t ha-1 (rainfall VI-VIII 270 mm). Production results of sprinkler irrigation were inversely correlated with the rainfall during the vegetation period. The highest yield increases (19.05 t ha-1) were obtained when rainfall in June-August amounted to 90 mm, while the lowest yield increases (7.82 t ha-1) – when rainfall in June-August amounted to 270 mm.