The aim of the study was to investigate whether plasma irisin concentrations differ between uncomplicated, early-onset and late-onset pre-eclamptic pregnancies. This cross-sectional study was conducted on 27 women with early-onset, 27 women with late-onset pre-eclampsia (PE) and 26 healthy pregnant women. Maternal levels of serum irisin were measured with the use of an enzyme-linked immunosorbent assay kit. The mean maternal serum irisin level of early-onset PE was significantly lower than late-onset PE (1.140.56 vs. 1.460.59, p<.05) and control subjects (1.140.56 vs. 3.14 +/- 0.81, p<0.001). The mean maternal serum irisin level of late-onset PE was significantly lower than the control group (1.46 +/- 0.59 vs. 3.14 +/- 0.81, p<0.001). Maternal serum irisin levels are decreased in pre-eclamptic pregnancies. Low levels of irisin may be the result or the cause of pathologic changes in PE.Impact statementWhat is already known on this subject? There are only two studies in the literature evaluating maternal serum irisin levels in pre-eclamptic pregnancies. One study demonstrated decreased maternal serum irisin levels in pre-eclamptic patients and the other found no significant difference between pre-eclamptic and control pregnancies.What do the results of this study add? The present study demonstrates that serum irisin levels were significantly lower in pre-eclampsia than normotensive pregnancies. Furthermore, we have also demonstrated for the first time that women with EO-PE had significantly lower levels of serum irsin than women with LO-PE.What are the implications of these findings for clinical practice and/or further research? Low levels of irisin may be the result or the cause of pathologic changes in pre-eclampsia. More studies are needed to evaluate the relationship between irisin and pre-eclampsia.