Three trials were conducted with pigs at different levels of nutrition. Seven groups of pigs were perorally infected with a suspension of M. intracellulare. Changes in 12 biochemical parameters of metabolism were studied in blood plasma or serum for 98 to 111 days. In comparison with the group of non-infected animals or with the situation prior to infection, the test pigs showed irregular and temporary changes in a number of metabolites, most frequently an increase in the concentration of urea, cholesterol, iron and vitamin A. In the majority of cases, the results are considered as non-typical of infection processes. It was also in relation to clinical and production parameters that the induced mycobacteriosis was regarded as a condition not disturbing, or just insignificantly influencing, the metabolism of slaughter pigs and the economy of their production. The changes in tocopherolaemia, reduction in alkaline phosphatase activity, increase in the total concentration of protein, albumin and cholesterol were related to the development of the pigs at the weight from 20 to 80 kg, rather than to the infection process. The limited intake of proteins or vitamin supplement allowed for verifying the possibility of using some biochemical parameters for practical diagnosis.