This paper summarises the recently introduced fat tax in Denmark, which came into force on 1 October 2012, and discusses some of the consequences of introducing the tax. Furthermore, this paper discusses the theoretical background and reasoning for imposing a fat tax as well as some of the problems and concerns stated, especially by the industry. The fat tax is a tax paid per kilogram of saturated fat in the following foods if the content of saturated fat exceeds 2.3 g/100 g. These include meat, dairy products and animal fats that are rendered or are extracted in other ways, edible oils and fats, margarine and spreadable blended spreads. The declared aim of the tax is to reduce the consumption of saturated fat among the Danish population in order to decrease the prevalence of diet-related illnesses. The tax is part of a larger reform of the Danish tax system with the general aim of decreasing the income taxation pressure and financing it by, among other things, increased environmental and energy taxes, as well as increased ‘health’ taxes. Pre-tax simulations predict that the health tax on saturated fat will give rise to a reduction in the consumption of saturated fat of approximately 8%.