Objectives The aim of this study was to explore the expression of the Hedgehog signalling pathway proteins, PTCH1 and GLI3, which are important regulators of foetal growth and development. We compared their expression in human placentas with IUGR and term placentas of heathy pregnancies. 9.2. Study design Firstly, we processed the samples histologically and then with immunohistochemical methods. PTCH1 and GLI3 proteins were marked with anti-PTCH1 and anti-GLI3 antibodies, then we used En VisionTM procedure. Protein expression was quantified using thestereological method. 9.3. Participants and methods Research was done on human placentas of women who had given birth at Merkur Clinical Hospital. We analysed 15 term placentas from heathy pregnancies without complications and 15 term placentas with IUGR pathology. We treated samples with following methods: immunohistochemistry, stereology, then analysed them using Student's t-test, ANOVA, Mann-Whitney and Kruskal-Walis's tests. 9.4. Results Expression of PTCH1 and GLI3 proteins was significantly increased in term placentas with IUGR in relation to controls (placenta tissues from pregnancy without complications) (p<0.0001; Mann-Whitney test). Also, GLI3 expression in term IUGR placentas and in control healthy placentas were statistically significantly increased in regard to PTCH1 expression. Results obtained are in accordance with those from other researches where negative regulators of trophoblast invasion (like PTCH1 and GLI3) were also increased in IUGR placentas. 9.5. Conclusion PTCH1 and GLI3 protein expression in IUGR placentas are significantly increased in comparis on to their expression in term placentas of heathy pregnancies.