Background/objectives The rise of nutrition-related diseases in developed countries prompts investigation into the role played by changing food patterns. Our aim was to observe changes in food-at-home purchases by French households and their impacts on nutritional quality over the past 40 years (1969–2010). Subjects/methods Time-series of food-at-home purchases from representative samples of French households were built based on two sources of data: the INSEE National Food Survey (1969–1991) and the Kantar Food Consumption Panel (1989–2010). Food-at-home purchases were converted into energy and nutrients using the French CIQUAL food composition table. The nutritional quality of food-at-home purchases was estimated using the mean adequacy ratio (MAR) for 15 key nutrients. MAR was expressed per 2000 kcal to assess the nutrient density of food-at-home purchases. Results Between 1969 and 2010, food-at-home purchases showed dramatic changes in many food groups, with increasing processed vs raw products. The purchase of calories increased (+6.7%) and nutrient density improved (MAR per 2000 kcal + 12.9 points). However, this overall trend harbors heterogeneous patterns: food-at-home calories decreased and nutrient density improved up to 2002, but then calories increased while nutrient density stabilized. Conclusions The nutritional quality of French households’ food-at-home purchases improved over the last 40 years, as shown by increasing nutrient density. However, during the last decade, nutrient density ceased to increase and the purchase of calories increased, advocating a need for public action to promote healthier food purchasing patterns.