Traditional sheep production for meat and wool for meat and wool among small and medium-sized Chilean farmers has low profi tability. Therefore, there is interest in producing value-added, differentiated products. One alternative is the production of sheep milk and cheese. This article analyzes and discusses existing alternatives for modifying milk and cheese compositions with the aim of differentiating these products. Also, analytical techniques that allow the chemical characterization of milk and cheese are briefl y mentioned. The main international thrusts are focused on the modifi cation of the content and composition of milk fatty acids and on the identifi cation of volatile compounds, terpenes, polyphenols and other analytes that allow differentiation of cheese types on the basis of aroma, taste and fl avor and that would help in ensuring traceability.