The objective of the study was the comparison of optimal precipitation and deficits of atmospheric precipitation in relation to millet cultivated in the region of Bydgoszcz and Wrocław in the period 1975-2014. In the region of Wrocław water needs in millet cultivation were larger than in the region of Bydgoszcz. In the growing season (from May to August) they amounted to 253 mm and 242 mm respectively. July was the month when the largest water needs were observed - 74 and 72 mm respectively. It was also discovered that in the region of Wrocław the optimal amount of precipitation in the millet growing season (from May to August) systematically increased in subsequent decades, from 234 mm in the period 1975-1984 to 266 mm in the period 2005-2014. The correlation and regression analysis showed that the increasing trend of changes of that index in time was significant. Monthly deficits of precipitation in the millet growing season - both maximum and average - were in each case larger in the region of Bydgoszcz. The largest maximum and average insufficiencies of precipitation occurred in July. The frequency of occurrence of years with insufficient precipitation was also larger in each month in the region of Bydgoszcz. The frequency of occurrence of years with extremely dry, very dry and dry millet growing seasons was larger in the region of Bydgoszcz (42.5%) than in the region of Wrocław (37.5%).