The purpose of this study was to determine the phenological development and the nutritional quality of Sorghum almun during different growth stages. The seed was cultivated in the Alfredo Volio Mata Experimental Station of the University of Costa Rica. Eighteen kg of 88% germinal seed per hectare were planted. The first sample was taken 24 days after sprouting and every 14 days thereafter, up to 150 days. The production of biomass of the stems, leaves and ears of grain were measured and the amounts (content) of dry mater matter, crude protein, total ashes, neutral fiber and detergent acid, hemicellulosa, cellulose and lignin were determined. During the first 52 days of growth, the output of leaves was higher than that of stems. On the 57th day, a yield of 1395 kg of dry matter per hectare, 50% leaves and 50% stems, was estimated. The ears of grain appeared after 94 days, contributing 50kg per hectare of dry matter. The concentration of dry matter in the leaves was highest from the moment of sprouting to the 136th day. The content of crude protein in the leaves was always superior to that in the stems. In the leaves the crude protein diminished 16%-28% between the 38th and 150th day of growth. In the same period, the crude protein in the stem diminished 5%-18%, and in the whole plant 8%-26%. The neutral fiber and detergent acid in the leaves and the stems were less than 60% during the first two months of growth and more than 70% in the latter period.