Introduction: Pregnancy causes changes in the hormonal balance, musculoskeletal, cardiovascular and lymphatic systems. The swelling of the lower limbs may also be one of the consequences of the enlarging uterus that increases body weight during pregnancy. Determination of the serum concentrations of myeloperoxidase - MPO, extracellular matrix metalloproteinase - MMP, and intreleukine-6 - IL-6 allows for the assessment of inflammation. MPO belongs to the group of peroxidase enzymes with strong antibacterial and anti viral action. It is produced and released from the granules of neutrophils in inflammatory reactions, degenerative changes and neoplasmatic diseases. IL-6 is the main mediator of the inflammation in the live organism, released by monocytes and macrophages stimulated by interleukin-1. Objective: To assess the levels of inflammatory mediators: MMP, MPO and IL-6 in women in the third trimester of pregnancy, both healthy and those who experienced idiopathic edema of the lower limbs. Material and methods: We analyzed the changes in the concentration of biochemical parameters as: MMP-1, MPO and IL-6 in the serum of 20 healthy pregnant women between 36 and 40 weeks of gestation, and 8 pregnant women who developed idiopathic edema of the lower limbs. The R&D Systems Elisa tests were used to perform the measurement. The Quantikine Human IL-6 Immunoassay was used to measure the concentration of IL-6. The concentration was expressed in pg/ml. MMP-1 was measured using The Quantikine Human Pro –MMp-1. The value of MMP-1 concentration was expressed in ng/ml. MPO was measured using The Quantikine Human MPO Immunoassay and expressed in ng/ml. Results: The mean concentration of IL-6 was higher in the group of pregnant women with swelling of the lower limbs (group II) in comparison to healthy pregnant women (group I) and it was approximately 3,01 pg/ml, SD=2,64, and 2,3 pg/ml, SD=1,92, respectively. No statistical difference was found (p=0,436). Parity has no influence on IL-6 concentration. The mean concentration of MPO in group I was 1797,04 ng/ml, SD= 1378,89, in II group it was 1702,54 ng/ml, SD=1289,64. (p=0,866). Parity has also no influence on MPO concentration. The mean concentration of MMP-1 in group I was 7,61 ng/ml, SD=4,6, in group II it was 10,46 ng/ml, SD=4,03. (p = 0,137). Significantly higher results were observed in primiparas with lower limbs swelling- 11,36 ng/ml when compared to multiparas – 9,57 ng/ml. Conclusions: 1. There are no significant differences in the concentrations of the studied inflammatory mediators between the groups of healthy pregnant women and those with idiopathic edema observed in the lower limbs. The significance of these differences requires further confirmation. 2. There was a statistically significant difference between the concentrations of MPO in the group of primiparas with a multiparas with lymphatic edema.