We study the price response of national brands to the development of private labels. We use monthly data from a consumer survey reporting their purchases for 218 food products. We show that when private labels have a significant effect on national brands prices (144 cases over 218), that is positive (89%). We also show that the increase in the prices of national brand products is explained by a strategy of product differentiation. Finally, price reaction of national brands differs with the type of private labels they are facing. This paper confirms, on a larger number of products, previous empirical results.