Protein and amino acids were measured in seeds of 5 soy bean cultivars (Cabrillo, Rillito, Duocrp, CM-3 and RK-315). Cabrillo was found to countain the highest protein content (41. 46%) and RK-315 the lowest (38. 96%). Sixteen amino acids were detected and determined in the protein hydrolyzates; their concentration varied. Essential amino acids like leucine, Isoleucine, lysine, methionine, threonine, valine, phenylalanine were found in different quantities according to cultivars. Glutamic acid and arginine ranged between 900-1200 and 364-454 mg/g total nitrogen in the varieties.