A greenhouse experiment was carried out to verify the effects of potassium on growth, yield and nitrogen, phosphorus and potassium absorption of 5 grain sorghum cultivars. Sorghum plants were grown in 20 1 pots, in presence either of full strengh solution, or potassium diluted to 0.5, 0.2 and 0.1 of normal concentration. At harvest (110 days from germination) the plants were split into several parts, oven dried, and ground. The samples were then analysed for total nitrogen, phosphorus and potassium. The potassium levels in nutrient solution afected the dry weight of sorghum grains; effects onthe dry weight of the other plant parts were not observed. The absorption of nitrogen, phosphorus and potassium decreased with the decrease in potassium supply; but only the nitrogen translocation to grains was afected by potassium levels in nutrient solution.