There are about 40 species in the Pleurotus genus, including those with high economic significance, i.e. P. ostreatus and P. pulmonarius. The fruiting bodies of oyster mushrooms are of high nutritional and health-promoting value. In addition, many species belonging to the Pleurotus genus have been used as sources of substances with documented medicinal properties, such as high-molecular weight bioactive compounds (polysaccharides, peptides and proteins) and low-molecular weight compounds (terpenoids, fatty acid esters and polyphenols). The bioactive substances contained in the mycelium and fruiting bodies of Pleurotus species exhibit immunostimulatory, anti-neoplastic, anti-diabetic, anti-atherosclerotic, anti-inflammatory, antibacterial and anti-oxidative properties. Their multidirectional positive influence on the human organism is the result of interaction of bioactive substances. Extracts from individual Pleurotus species can be used for the production of dietary supplements increasing the organism’s immunity. They are also used for the production of cosmetics. They can be added to functional foods as probiotics, or used as natural preservatives or ingredients of special foodstuffs for patients with specific diseases.