This experimental study was designed to determine effects of Nigella sativa oil (NSO) on endothelin-1 (ET-1) level and oxidative stress parameters, superoxide dismutase (SOD) and malondialdehyde (MDA) in a rat sepsis model. Twenty four adult Wistar albino rats were divided randomly into three groups: sham group (group 1), sepsis group (group 2), sepsis group pretreated with NSO (group 3). Serum ET-1, tissue SOD and tissue MDA levels were measured in all groups. Compared to group 1, ET-1 and MDA levels were higher in group 2. ET-1 and MDA levels in NSO pretreated group 3 were lower with respect to group 2 (p<0.03, and p<0.02, respectively). Additionally, SOD levels in group 3 were found to be higher than group 2 (p<0.02). Based on our results, it can be concluded that NSO may have a positive impact on ET-1 levels and oxidative stress induced by sepsis in experimental rat models.