The objective of this study was to determine carcass quality of fatteners of Swallow-belly Mangalitsa breed reared in outdoor system. In m. longissimus dorsi (MLD) samples chemical composition, cholesterol content and fatty acids profile was determined. The study included 22 castrated males reared in the oak forest from the early spring to late autumn, with minimal corn harvest (approx. 0.5 kg per day). During the winter, the fatteners were kept in wooden stables and fed with cereals (corn and barley mixture in a ratio of 70:30, approx. 3 kg per day). The data was carried out by statistical package SAS 9.1.3 (SAS Inst. Inc., 2002-2003) and basic statistical parameters are showed (Mean±SD). At the end of fattening, the pigs were about one year old, and slaughtered at 92.0±16.7 kg live body weight. The average lean content in the carcasses was 35.9±2.8 %, while the content of intermuscular fat in MLD was 6.2±1.2 %. In the MLD samples average content of proteins, water, fat and ash were 20.7±0.5 %, 70.4±0.5 %, 7.7±0.5 % and 1.0±0.1 %, respectively. Average cholesterol content was 41.4±3.8 mg/100g. Shares of saturated fatty acids (ΣSFA) in MLD fat was 35.6±1.2 %, monounsaturated fatty acids (ΣMUFA) was 56.6±1.8 % and polyunsaturated fatty acids (ΣPUFA) was 6.9±1.2%. Within ΣSFA the most common was palmitic acid (C16:0, 24.7±0.6 %), wile within ΣMUFA it was oleic acid (C18:1c-9, 46.9±1.1 %) and within ΣPUFA it was linoleic acid (C18:2n-6, 5.6±1.0 %). ΣPUFA and ΣSFA ratio was 0.2±0.0, while omega-6 and omega-3 ratio was 25.1±5.6. Showed ratios are not desirable from the nutritional aspect of human diet.