Food proteins contain latent biofunctional peptide sequences within their primary structures which may have the ability to exert a physiological response in vivo. A large range of biofunctional peptides have been isolated from food proteins including opioid, immunomodulatory, antimicrobial, mineral binding, growth and muscle stimulating, anticancer, proteinase and angiotensin converting enzyme (ACE, EC 126.96.36.199) inhibitory peptides. The biofunctional peptide activity currently most studied in food proteins appears to be those that inhibit ACE. ACE plays a central role in the regulation of blood pressure (BP) through the production of the potent vasoconstrictor, angiotensin (Ang) II , and the degradation of the vasodilator, bradykinin (BK). ACE inhibitory peptides may therefore have the ability to lower BP in vivo by limiting the vasoconstrictory effects of Ang II and by potentiating the vasodilatory effects of BK. These ACE inhibitory peptides can be enzymatically released from intact proteins in vitro and in vivo during food processing and gastrointestinal digestion, respectively. ACE inhibitory peptides may be generated in or incorporated into functional foods in the development of ‘natural’ beneficial health products. Several products are currently on the market or are in development that contain peptide sequences which have ACE inhibitory properties. Detailed human studies are required in order to demonstrate the efficacy of these bioactive peptides prior to their widespread utilisation as physiologically beneficial functional foods/food ingredients.