The aim of the work was to determine the effect of sterilization of pork in the presence of oxidized lard and selected antioxidants on quantitative and qualitative changes of thiamine in pork. The antioxidants were casein hydrolizate and rosemary extract. It was found that sterilization itself caused the greatest losses in both forms of thiamine. In the case of adding fresh lard to the meat, the total thiamine losses were 58%, and introduction of the oxidized fat increased the losses to 63%. The bound thiamine determined the size of the losses. Application of rosemary extract with fresh fat during thermal processing lowered the loss of the bound thiamine by 5%, while casein hydrolizate contributed to decreasing the loss of the bound thiamine by 4.5%. In the presence of the oxidized fat, a similar protective activity with respect to thiamine of both antioxidants was found with better effect obtained with casein hydrolizate.