This review presents available evidence for possible application of n-3 long chain polyunsaturated fatty acids (PUFAs) in pregnant obese women with metabolic syndrome (MS) and focuses on prophylaxis of pregnancy complications associated with MS such as gestational hypertension, preeclampsia and gestational diabetes. Dietary supplementation with n-3 PUFAs has recently become popular and their adequate intake during pregnancy and early childhood is of clinical importance. The results of experimental and epidemiological investigations reveal that n-3 PUFAs, especially α- linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), may decrease the risk of cardiovascular diseases. It is believed that n-3 PUFAs affect a multitude of molecular pathways, involving regulation of gene expression, alteration of physical and chemical properties of cellular membranes and modulation of membrane channels and proteins. A large body of evidence focuses on anti-inflammatory properties of PUFAs which seem to be fundamental in prevention and reversing of insulin resistance, atherogenic dyslipidemia, hypertension, thromboembolism and in improving vascular function. Despite the potential PUFAs benefits of decreasing insulin resistance, their application in order to prevent preeclampsia, gestational hypertension and gestational diabetes mellitus in pregnant women with MS has not yet been established. Numerous reports have revealed that appropriate fetal development, including neuronal, retinal and immune function depends on EPA and DHA which are crucial also for prevention of preterm birth. Thus the supplementation with EPA and DHA is highly recommended during pregnancy although the optimal dosing and treatment strategies still need to be determined.