Thanks to the work of many dedicated researchers and particularly the team of Prof. Q. R. Rogers and Prof J. G. Morris, at the University of California, Davis, our knowledge of the nutritional needs of cats has expanded greatly over the last 30 years. It is now appreciated that cats require a specialized diet formulated for their specific nutritional needs (AAFCO 1998, NRC 1986). Those specific needs are most probably the result of their long history as flesh eaters that lead into modifications of enzyme activities and thus, nutrient metabolic pathways (MacDonald, 1984). The purpose of this paper will be to highlight those peculiarities that have to be taken into account in the formulation of commercial cat food.