Many studies have been performed to clarify the action mechanism of some legume protein that exert the cholesterol-lowering property. On previous studies, we have verified the hypocholesterolemic effect on performed with the β-vignin isolated from cowpea, in animals. Here, we evaluated the peptide fractions derived from β-vignin hydrolyzed for their capacity to inhibit the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, in vitro. Cowpea β-vignin was isolated, chromatographed and characterized. Briefly, the procedure of isolation consisted many steps based in suspension e precipitation process of the protein. The protein isolated was chromatographed by size exclusion on Sepharose CL-6B column (1.0 x 100 cm). The protein eluted was monitored by measuring absorbance at 280 nm. The main fraction was collected, dialyzed against distilled water, and then lyophilized. The β-vignin chromatographed was used to hydrolysis procedure by pepsin/pancreatin action. Subsequently, the total protein hydrolyzed was fractionated on peptide fractions to different molecular weight were fractioned (peptides large than 30 kDa, 30 to 10 kDa, 10 to 3 kDa and peptides smaller than 3 kDa). These fractions were used to evaluate the inhibition capacity over HMG-CoA activity, in vitro. The total hydrolyzate and peptide < 3 kDa obtained from β-vignin have exerted a significantly decreased of HMG-CoA activity when used 0.5 mg/protein/mL. Under the same experimental conditions, the peptide fractions of 30 to 10 kDa and 10 to 3 kDa showed inhibit to HMG-CoA activity on a level over 50%. The fraction that has exerted the best inhibition was formed by four main peptides (peptides less than 3 kDa). Currently, our group is studying these majority peptides. We have expectation towards the identification of peptides that may present some hypocholesterolemic property, and there by advance in the elucidation of their possible mechanisms of action.