A generalized inflammatory response has been considered to be the main pathology and has an important role in the pathogenesis of preeclampsia. The immune aberrations per se and immunomodulatory milieu present in serum need to be elucidated. The purpose of the current investigation was to characterize changes in serum levels of interleukin (IL)-15 and IL-16 in preeclampsia. Thirty-seven women with preeclampsia were recruited and 36 age- and gestational age-matched women with normal pregnancy served as control. Levels of IL-15 and IL-16 were detected with immune assays in all serum samples. We found that serum levels of IL-15 and IL-16 were significantly higher in preeclampsia than in normal pregnancy (p<0.001 for both). There were significant differences in serum IL-15 and IL-16 between mild and severe preeclampsia (p<0.01 for both). Our data corroborate the hypothesis of an increased inflammatory response in preeclampsia, as illustrated by the elevated serum levels of IL-15 and IL-16, suggesting their possible role in the pathogenesis of preeclampsia. These associations may offer insight into the pathophysiology of preeclampsia.