The physiopathological effects were studied of a common high erucic acid rapeseed oil as well as of Janpol, a low erucic acid oil produced of a rapeseed variety selected in Poland. Its erucic acid content equals 2.8% of total fatty acids. The studies were carried out on white male Wistar rats, 25 days old at the beginning of experiment. These animals were divided into 6 groups fed the diets in which 10 or 20% of kcal well supplied either by high erucic acid rapeseed oil, by Janpol rapeseed oil, or by the sunflower oil. The experiment lasted 6 months. Following parameters were determined: increase in body weight, the weight of selected organs, blood serum alkaline phosphatase and pseudocholinesterase activities, blood serum cholesterol and triglycerides level, the content of corticosterone in the adrenal glands and blood plasma. The liver was studied histochemically for the activity of acid and alkaline phosphatases and of ATP-ase, as well as for the presence of lipids. Morphological studies of the myocardium comprised macroscopic, histological and electron microscopic investigation. The low erucic acid rapeseed oil Janpol seems to evoke less disturbances than the high erucic acid one. Supplied in the amount corresponding to 10% of total calories intake the former exerts the effect on the biochemical and morphological parameters similar to that of sunflower oil. It can be thus assumed that the low erucic acid rapeseed oil Janpol can be used in the feeding of man when served in the amount lower than 10% of total calories.