Abstract Objectives: Uterine myomas may change the concentrations of the screening serum markers and therefore alter the risk calculation of the fetal chromosomal abnormalities. An increased risk leads to invasive diagnostics procedures which in these cases can often be technically difficult due to the presence of myomas. Aim: The aim of this study was to assess the influence of uterine myomas on the first and second trimester serum markers concentrations and, possibly, on the test results. Material and methods: The study group consisted of 127 women between 11 and 20 weeks of normal singleton pregnancy. In each case uterine myomas were diagnosed – over 20 mm in the diameter and located in the uterine wall. 77 patients underwent the first trimester screening (PAPP-A & free β-hCG) and 50 patients had the second trimester screening (triple test). The control group consisted of 1020 women between 11 and 20 weeks of normal singleton pregnancy without uterine myomas. Delfia Xpress analyser was used for the serum markers estimations. All pregnant women delivered normal healthy babies. Results: In the first trimester group the PAPP-A serum concentrations were not different from the controls while the mean median concentration of free β-hCG were significant higher – 1.43 MoM. In the second trimester group the following mean median values were observed: no significance for the AFP – 1.18 MoM and estriol – 1.29 MoM and significantly higher mean median value for the free β-hCG – 2.01 MoM. Conclusions: 1. The presence of the uterine myomas is connected with the increased maternal serum concentration of the β-hCG, particularly in the second trimester. 2. The uterine myomas may lead to the increased rate of the false positive results of the prenatal screening test, especially the triple test.