Introduction and aim. Information concerning lactoferrin and interleukin-8 (IL-8) local levels in breast milk are not numerous and requires further research. The aim of this study was to determine the content of lactoferrin and interleukin-8 in the breast milk of patients with lactational mastitis, and to identify new potential markers for assessing the activity of the inflammatory process in the mammary gland. Material and methods. This study analyzed the breast milk of 30 women with lactostasis (group I), 37 women with lactational mastitis (group II) and 30 healthy lactating women (age 26±5 years old). The milk content of lactoferrin and interleukin-8 (IL-8) was determined by enzyme-linked immunosorbent assay. Results. The average value of lactoferrin in breast milk of healthy women was 4.78±0.47 mg/mL, exceeding levels in group I 1.8 times (p<0.05). The level of lactoferrin in group II exceeds the control values 3.1 times (p<0.05). The content of IL-8 in breast milk of women in group I was 7.3 times higher than the control (3.63±0.12 pg/mL, p<0.05). In lactational mastitis, the concentration of IL-8 in breast milk exceeded the group I 13.9 times (p<0.05) and was 1.9 times higher than group I (p<0.05). Conclusion. The analysis has revealed an increase of lactoferrin and IL-8 in breast milk of the test groups, which indicates the activation of non-specific protection.