This study was carried out to determine the effects of nigella sativa oil on the doxorubicin (DOX) cardiotoxicity in rats. In the study, rats were divided into 4 groups: Group 1: Control group, Group 2: Nigella sativa oil-treated group (2 mL/kg/day gavage, 7 days), Group 3: DOX-treated group (20 mg/kg body weight, single dose, i.p.), and Group 4: DOX (20 mg/kg body weight, single dose, i.p.) + nigella sativa oil (2 mL/kg/day gavage, 7 days) treated group. Nigella sativa application was started 2 days before DOX application and continued for 7 days. At the end of the study, malondialdehyde (MDA), reduced-glutathione (GSH) levels, and antioxidant enzymes activities such as catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and glutathione-S-transferase (GST) were determined. In the DOX-treated group, there was an increase in MDA (P<0.001) and GSH (P<0.001) levels, and a decrease in CAT (P<0.001), GSH-Px (P=0.024), and GST (P<0.001) activities compared to the control group. There was no statistically significant difference in SOD activity. MDA, GSH levels and CAT, GSH-Px and GST activities were found to be reached to the values of control group in the DOX+nigella sativa treated group compared to the DOX-treated group. As a result, Nigella sativa oil has been shown to protect heart tissue against oxidative damage caused by DOX, a potent chemotherapeutic drug.