The characteristics of dairy products depend on both the processing technology and the chemical and microbiological characteristics of milk. The milk properties depend themselves on a number of production factors linked to animals (genetic and physiology) or feeding. Some of these factors, the way animal are fed in particular, are increasingly becoming the focus of consumers’ concern. In particular, grass-based diets are sensitive because grass carries a positive image that can be attractive to some, because it may confer special nutritional characteristics to the products and also because grass feeding is part of the basic link between products and their original land which is important in the case of labelled products (Protected Denomination of Origin [PDO]). The aim of this text is to take stock of the recent studies (Coulon et al., 2004), which have studied the effect of grass on the sensory qualities of cheeses and butter. Other dimensions of quality. i.e., health and nutrition, are not investigated.