In small-plot experiments established in 2001–2004 we studied the effect of the chemical composition of the plant dry matter of spring barley, varieties Kompakt and Jersey, on grain yields. A re­la­ti­ve­ly strong correlation was confirmed between the chemical composition of the plant dry matter and yields. The correlation was most intensive in the case of nitrogen (r = 0.536), phosphorus (r = 0.503), magnesium (r = 0.464) and sulphur (r = 0.431) at the beginning of shooting (DC 30); in the case of potassium (r = 0.557) at the beginning of tillering (DC 23) and calcium (r = 0.530) during ear formation (DC 55). A relatively strong correlation remained from the beginning of tillering to the beginning of ear formation and later decreased. The weather conditions of the year and variety significantly affected grain yields and also the previous crop was important. Grain yields of the variety Kompakt were statistically significantly lower than of the variety Jersey (6.02 t . ha−1 and 6.45 t . ha−1, respectively). The yields of barley grown after sugar-beet were the highest (6.30–6.79 t . ha−1); the grain yields of barley after maize decreased by 9.1–9.7 %. Higher grain yields of the Jersey variety resulted in levels of ­N-substances (11.35 %) lower than in the Kompakt variety (11.35 % and 11.60 %, resp.). No correlation was discovered between the nitrogen level in the plant dry matter during vegetation and the content of ­N-substances in barley grain.