In this article, the immunomodulatory, antioxidantive, anti-microbial, anti-inflammatory, anti-hypertensive, anti-diabetic, anti-cancer, mineral-binding and cholesterol-lowering effects and opioid activities of physiologically active or bioactive peptides are discussed. Specific and small protein particles that have a positive impact on human metabolism or body conditions are called bioactive peptides. Bioactive peptides primarily affect gastrointestinal system, nervous system, cardiovascular system and immune system. These peptides are very important for pharmaceuticals and functional food formulations because of their beneficial properties for human health. Empiric and bioinformatics studies have provided important information and nowadays, thousands of bioactive peptides identified.