This study has analyzed the effect of fertilization with various forms of nitrogen and sulphur on cocksfoot yield and on the content of these nutrients in the plant. The study was based on a strict experiment conducted on soil material from the arable layer of brown soil of clayey silt granulometric composition. The soil used in the experiment was characterized by slight acidity and low content of assimilable forms of phosphorus, potassium, magnesium and sulphur. The results indicate that the experimental factors caused significant variation in cocksfoot yield. Significant variations in yield also occurred as a result of the interaction between these factors. The highest yields were obtained where nitrogen was applied in the liquid form (UAN-30) and sulphur was applied in the form of Na2SO4. Significant increases in yield after application of elemental sulphur were not observed until the second cut was harvested, which clearly indicates that this is a slow-acting fertilizer. Fertilization with various forms of nitrogen and sulphur also caused marked variation in total S content, total N content and N-NO3 in the plants. Total sulphur content – depending on the experimental object and on the time of harvest – ranged from 1.37 to 3.15 g S kg-1, while total nitrogen content ranged from 29.06 to 38.72 g N kg-1. The data obtained indicate that sulphur content in plants that were not fertilized with this nutrient was much lower than is considered optimal for grasses. This explains the effect of sulphur on yield observed in the experiment. Fertilization with sulphur also had a beneficial effect on nitrogen metabolism, manifested as a more than twofold decrease in nitrate nitrogen in the plants fertilized with sulphur.