The aim of the study was to evaluate selected parameters of the milk of mink receiving a plasma supplement and to assess the health status of the mammary gland of these animals. The studies were conducted on American mink (Neovison vison). Two groups of animals were formed: the experimental one, which received 0.5% beefpork plasma in a daily dose of feed, and the control group, which received no plasma. The milk parameters measured were the contents of fat, protein, lactose, and dry matter, as well as the somatic cell count in 1 ml of milk. Both groups were examined for mastitis three times (in weeks 1, 2 and 3 of lactation). In the milk of animals receiving dried blood plasma, there were significant differences in the contents of fat, lactose, and dry matter, as well as in the somatic cell count. The examination of the mammary gland for mastitis showed positive effects of plasma supplementation. The results obtained suggest that supplementation with dried blood derivatives may favorably affect the animal’s immune system and strengthen the first line of defense against environmental microorganisms.