Data on production traits of the only Slovenian autochthonous pig breed, the Krškopolje pig, is very scarce. Krškopolje pigs are reared in conventional and organic production systems, which were compared in the present study. After weaning, 24 barrows were assigned within litter to either conventional (CON) or organic (ECO) rearing system. Group CON (n=12) was housed indoors in two pens (7.5 m2) with partly slatted floor. Group ECO (n=12) was held in a sty with sheltered area (concrete floor, bedded with straw, 16 m2) and outdoor paddock area (100 m2). The trial started when pigs had 68±8 kg BW and 157±6 days of age. Two diets were formulated with equivalent ingredients and composition. For ECO diet the ingredients used were ecological. Group ECO received a diet with 12.4 MJ metabolisable energy (ME) per kilogram and 12.9% CP and group CON a diet with 12.7 MJ ME/kg and 13.6% CP. Feed distribution was limited to 3.5 kg per pig daily. In line with the rules for organic production, ECO pigs were additionally given alfalfa hay ad libitum. After 73 days on trial, the pigs were slaughtered and carcass, meat and fat quality was evaluated. Meat quality traits (pH, colour, water holding capacity), fatty acid composition, lipid and protein oxidation, collagen content and solubility were analysed in longissimus lumborum (LL) muscle. Fatty acid composition, lipid oxidation, and vitamins A and E concentrations were determined in backfat. There were no significant differences in growth rate and carcass traits between ECO and CON pigs, however, ECO pigs tended (P<0.10) to have higher daily gain and lower dressing percentage, higher (P<0.001) pH 45 min and lower (P<0.01) pH 24 h postmortem, affecting (P<0.10) also water holding capacity and objective colour parameters (P<0.05) of LL muscle. There were no differences in intramuscular fat (IMF) content of LL muscle, however, IMF of ECO pigs had lower (P<0.05) proportion of saturated and higher (P<0.01) proportion of monounsaturated fatty acids accompanied by higher (P<0.001) values of thiobarbituric reactive substances (TBARS). In backfat, ECO pigs showed lower (P<0.05) vitamin E content, higher (P<0.001) TBARS, higher (P<0.01) degree of unsaturation (percentage of polyunsaturated fatty acids), and also higher (P<0.05) vitamin A concentration than CON pigs, which can be related to alfalfa hay supplementation of ECO pigs. In brief, organic rearing of Krškopolje pigs did not affect performances but had an effect on meat and fat quality.