The study of the nutritive value of Cowpea (Vigna ungiculata L.) legume seed is needed, as this legume is a food source in many developing countries. Whole Cowpea Flour (WCF), Dehulled Defatted Cowpea Flour (DDCF), and Cowpea Protein Isolates (CPI) prepared using Isoelectric method (CPII) and using Micellization method (CPIM) are studied. In proximate analysis, the protein content of WCF, DDCF, CPIA and CPIB was found to be 22.3, 26.7, 750 and 76.0 g/100 g, respectively. Net protein value (NPV) was 17.62 for DDCF. Chemical score was 0.66% for DDCF and 112%, 104% for CPII and CPIM, respectively. The first limiting amino acid was cystine for DDCF and threonine for CPII and CPIM. Methionine was found to be the most concentrated essential amino acid in both CPII and CPIM; values were 27.22 and 30.60 g/16 g N, respectively, while lysine was the most abundant essential amino acid in DDCF (4.28 g/16 g N). Essential amino acids of CPIi and CPIM were 22.99 and 15.78 g/16 g N respectively, higher than FAO/WHO reference.