The purpose of this study was to determine the yield of biomass of corn in different stages of growth, cultivated in the higlands of Costa Rica as fodder for dairy cattle. It was carried out at the Alfredo Volio Mata Experimental Station of the University of Costa Rica. The first sampling was carried out after 37 days and every two weeks threafter through 149 days. Dry matter, crude protein, ashes, neutro detergent fiber (NDF), acld detergent fiber (ADF) and the lignin were analyzed. The value of hemicellulose and cellulose were calculate. The yield of green and dry biomass in the stems, leaves, flowers and fruit of the plant was measured at different stages of growth. Before 65 days, the yield of dry mateiral in the leaves was superior to that in the stems. Later the accumulation of dry matter in the stems was around three times greater then that in the leaves. The first blossoming occurred after three months. Two weeks later the first ears of corn were collected, thir highest yield occuring at four months. After 65 days, the relation leaves:stems was less than 1, predominating the accumulation of stems. This relationship slowly decresed as the plants became older. The concentration of dry matter in the stems was less than in the leaves at all growth stages. The content of crude protein (CP) in the stem was higher (18%) during the first 50 days, decresing to 11% at 80 days and threafter remined between 6.5% and 7.5%.