The effect of adding 5% powdered oyster mushroom (Pleurotus ostreatus) during 12 weeks on kinetic parameters of cholesterol metabolism was studied in male rats (Wistar, initial body weight 85 g) fed a semisynthetic diet containing 0.3% of cholesterol. The plasma cholesterol decay curve (examined for the final 29 days of the experiment after a single dose of cholesterol-4-14C) was evaluated by mathematical analysis using a two-pool model of plasma cholesterol metabolism. The oyster mushroom in the diet reduced the half-times of both exponentials resulting in lower calculated values (by 28%) of total entry of cholesterol into the body cholesterol pool (absorption+endogenous synthesis) and lower sizes of both pools (with slower and faster cholesterol exchange). The rate of cholesterol exchange between the pools was enhanced and the rate of total clearance of cholesterol from the system (metabolic turnover rate of cholesterol i.e. the rate of degradation and excretion of cholesterol from the organism) was enhanced by 50%. The oyster mushroom diet effectively prevented the progress of hypercholesterolaemia (decrease by 38%) and cholesterol accumulation in liver (decrease by 25%) that were induced by the cholesterol diet.