Proteins play an important role in body functioning. They can also be a good source of peptides with different activities. Such peptides are defined as biologically active (bioactive peptides). Bioactive peptides interact with proper body receptors and such an effect can be beneficial or not. Biopeptides as components of food with desired features have become an interesting issue for scientific research. Many of bioactive peptides are found in milk and dairy products, plant, animal and microbial proteins. They function mainly as inhibitors of the angiotensin converting enzyme but there is a plenty of peptides derived from other sources that can even prevent chronic diseases. This paper focuses on peptides derived from different sources and their physiological role in the body as well as functional aspects of their application in food production. In this article we concentrate on the peptides exerting the following activities: affecting blood pressure, prolyl endopeptidase inhibitors, coeliac toxic, immunomodulating and opioid.