The purpose of the research was to define the influence of cultivar, growing season and grain largeness on its extractivity, which was determined by Bishop’s formula. The experimental material was: barley grain of Rudzik, Brenda and Scarlett cultivars, from growing seasons of 2000-2003, originating from the region of Lower Silesia, taken from raw material supplied to malthouses, as well as grain from 10 cultivars of brewing barley (Class, Blask, Riviera, Lailla, Hanka, Sebastian, Bolina, Philadelphia, Tolar, Stratus), from the growing season of 2005, from Agricultural Experimental Station in Pawłowice In the fractionated barley grain there were determined protein content and thousand grains weight. Malts of Pilzen type were obtained as a result of brewing barley grain malting in laboratory conditions for 6 days. After mashing, there was determined the content of extract in congress worts. On the basis of extract content malt extractivity was calculated. These data were compared with the extractivity of barley grains, determined by Bishop’s formula and differences analyzed statistically. It was stated that the application of Bishop’s formula in the evaluation of the malting usability of brewing barley grain, especially in multi-year analyses, enables predicting the extractivity of Pilzen type malts with high accuracy. Differentiated cultivar-specific traits, changeable weather conditions during growing seasons as well as grains fractionation in terms of their thickness neither impair nor significantly change the effects of predicting the malting usability of brewing barleys with the formula of Bishop.