Leptin is stated to be an important mediator between obesity and cardiovascular disease. However, whether leptin location in the aorta is dependent on diet and its atherogenic character is still unknown. This study examined the relationship between a high-fat diet with or without cholesterol and the expression of leptin in aortic layers. Forty male rats were fed a high-fat diet with fish or grape seed oil as a dietary fat source, with or without cholesterol, to enhance the atherogenic character of their diet. The experiments lasted for three and six weeks, respectively. Plasma lipid profile, plasma leptin concentration and leptin expression in the endothelium (E), myometrium (M) and adventitia (A) were examined. The length of feeding was a key factor which influenced both the lipid profile and leptin expression in the aorta. Leptin concentration positively correlated with body weight and plasma triglycerides only in the three-week experiment, which suggests that the physiological actions of leptin can be disturbed by prolonged consumption of a high-fat diet. Short-term intake of a high-fat diet with fish oil, increasing high density lipoprotein cholesterol (HDL) level and decreasing total cholesterol (TC)/HDL ratio, enhanced leptin expression in E in comparison to the group fed grape seed oil. However, in the group with the highest diet intake, leptin expression in each layer was lowest. Generally, leptin expression was most common in E; however, an extension of the period of feeding in groups fed a diet with grape seed oil with or without additional cholesterol increased leptin presence in M and A in comparison to the group fed fish oil. Significantly higher values of TC and HDL in the same groups may suggest that leptin changes in the aorta and the atherogenic impact of grape seed oil can be connected when the consumption of a high-fat diet is excessive.