This paper estimates firm-level mark-ups and their volatility along the agri-food value chain using the methodology of De Loecker and Warzynski (2012). We estimate mark-ups of farmers, processors, wholesalers and retailers, how they change over time, and their volatility. We use detailed micro-level data from companies from Italy and France for the period 2006-2014. We find that farmers have a significantly higher volatility of mark-ups than other agents in the agri-food value chain, such as food processors, wholesalers and retailers. The volatility is negatively related with firms size in all sectors, and especially in agriculture.