Bioactive peptides are protein components which are inactive within the protein structure, and upon release by enzymatic hydrolysis, they exhibit special physiological functions. In the last years, the characteristics of bioactive peptides obtained from various plant, animal and microbial sources have received much attention. Bioactive peptides are produced using hydrolysis by enzymes extracted from plants or microorganisms, or digestive enzymes and fermentation by proteolytic starter cultures. The composition and sequence of the amino acids determines their different functions, including relaxing effects, solute binding properties, strengthening of the immune system, antioxidant, anti-microbial, anti-inflammatory, cholesterol-lowering and anti-hypertensive effects. Bioactive peptides are identified by different methods including membrane separation techniques and chromatography from protein hydrolysis products and using spectrometric techniques. The possibility of using bioactive peptides as health or therapeutic components depends on ensuring their bio stability, bioavailability and safety.