For over 40 years saturated fat, the fat found primarily in animal foods, was thought to be the main culprit for increasing cholesterol levels and causing heart disease. During this same time vegetable oils were promoted as being heart healthy because they could lower cholesterol. However, recently the evidence implicating saturated fat as being harmful to heart health has been challenged and more studies are beginning to show the harms from consuming industrially produced vegetable oils. Furthermore, monounsaturated fats, found in olives, olive oil, certain nuts and avocadoes have been promoted as being part of a healthy Mediterranean diet. This paper will provide a brief review comparing the effects of saturated fat to monounsaturated fat.