In this study, we investigated the relationship between serum level of IL-27 with preeclampsia and its severity. Fifty-six preeclamptic, 21 health pregnant and 20 health nonpregnant women formed the study group. The levels of IL-27 in maternal circulation were determined by ELISA. IL-27 serum levels were found to be elevated in healthy pregnant and preeclamptic groups as compared to non-pregnant women, this increase was significant in preeclamptic cases (p = 0.0004). Moreover, a significant difference of IL-27 serum level was observed between groups and the healthy pregnant controls, (p = 0.0095). Notably, the level of IL-27 was considerably elevated in women with severe preeclampsia, but not with mild preeclampsia as compared with healthy pregnant women (p = 0.0056, p = 0.0964, respectively). Furthermore, IL-27 serum levels were significantly differences in early onset and late onset sever preeclampsia than in gestation matched healthy pregnancies (p = 0.0376, p = 0.0085, respectively). In conclusion, our results suggest IL-27 might be a useful biomarker for disease severity in preeclampsia.