The study was conducted to compare animal performance and physicochemical properties of meat of entire males, surgically castrated or immunocastrated males of two Polish native breeds Pulawska and Zlotnicka Spotted, managed under the organic production system. The experiment was carried out on 60 pigs of the Pulawska breed and 60 of the Zlotnicka Spotted pigs. The animals (25 kg BW) were randomly allocated into 3 groups (20 pigs each): EM – entire males, SC – surgically castrated males and IC – immunocastrated males. The SC group was surgical castrated at 5 d of age, while the IC group was injected with 2 ml Improvac® Pfizer at 84 d of age and 4 wks before slaughter. The results indicated that the Pulawska breed gained weight and utilized feed better than the Zlotnicka Spotted, and meat of Pulawska breed was characterized by higher fat content. In the whole fattening period, the highest gains were achieved by the IC groups of both breeds, however it was statistically similar to EM group and higher by 8.5% than SC group (P ? 0.05). The carcass fatness of the IC group was similar to the entire males, whereas the carcasses of SC group were characterised by significantly higher backfat thickness (P ? 0.05). The castration type has not affected the meat acidity but significant effects were found in content of free water and shear force of meat which was much more tender in IC group. Also, the colour of meat in IC group was less saturated in yellow. Meat of SC group was characterised by higher fat content (P ? 0.05), in contrast to protein content which was lowest (P ? 0.05). Meat of the SC group was characterised by the lowest content of PUFA and the highest n6/n3 ratio as well as the thrombogenicity index. Summarizing the results obtained, this study proved that immunocastration, in comparison to surgical castration, improved the pig growing performance and feed conversion and decreased the backfat thickness of the carcass. Meat of immunocastrated males showed some favourable features in comparison to meat of surgically castrated males, i.e. it was more tender, had more favourable muscle textural parameters and lower PUFA n6/n3 ratio. Immunocastration type did not influence the content of androstenone and skatole – substances responsible for off-flavour aroma.