The hypocholesterolemic effect of plant sterols (phytosterols) that relies on lowering the intestinal absorption of both dietary and endogenous cholesterol has been known since the middle of the twentieth century. Due to this fact, many food products, mostly margarines, have been enriched with phytosterols and used in management of moderate hypercholesterolemia. Phytosterol-enriched margarines enable effective therapy of moderate hypercholesterolemia with dosage of around 3 g phytosterols per day. A higher dose is not recommended due to the possibility of interference of phytosterols with the absorption of fat-soluble vitamins. The characteristic feature of phytosterolemia (sitosterolemia) is enhanced absorption of phytosterols which in consequence leads to premature atherosclerosis. The objective of this review is to discuss the results of available studies concerning metabolic effects of phytosterols with a closer look at their impact on lipid metabolism in humans.