Preeclampsia (PE) is a common pregnancy-related hypertensive disorder and is a leading cause of maternal and perinatal morbidity and mortality. The incidence of PE and its associated health care costs have been increasing in the United States over the past three decades. Pregnancies complicated by PE put both the mother and child at increased risk for chronic illnesses such as cardiovascular disease, cerebrovascular disease, and cognitive impairment later in life. To date, there is no effective treatment for PE and the etiology of PE is largely unknown. While human epidemiological studies have established an association between various genetic factors and PE, a causative link between genes associated with PE and PE development has been difficult to establish. Human studies have shown that variants in eNOS (endothelial nitric oxide synthase, also known as NOS3) gene are associated with PE, and animal experimental studies have provided evidence to show the potential functional connection between the eNOS gene and PE. Here we review several studies that investigated the role of eNOS in PE, as well as studies that described how manipulating the eNOS/NO pathway could aid in disease intervention.