Increasing the potency of antihypertensive food-derived peptides is a critical and important step in the development of natural drugs for cardiovascular diseases prevention. We have proposed the egg-white protein precipitate (EWPP) obtained as a byproduct of cystatin and lysozyme isolation as a potential source of ACE-inhibitory peptides derived by pepsin digestion. The results indicated that hydrolysis of EWPP with pepsin produced the ACE inhibitory activity. During 3-h hydrolysis (DH: 38.3%), the IC50 value of EWPP hydrolysate was significantly increased and finally reached IC50=643.1 μg/mL. This hydrolysate was further fractionated by RP-HPLC. The peptide fraction exhibiting the highest ACE inhibitory activity was rechromatographed. Three peptide subfractions exhibiting ACE-inhibitory activities of 69.0, 25.0, and 37.6 μg/mL were further characterised. In each of them, mixtures of peptides with different molecular masses were observed.