Canteens are known to be promising settings for activities to promote intake of fruits and vegetables, but it remains unclear to what extent distributing free fruits and vegetables can influence dietary patterns of customers. The present study evaluated the effect of providing fruits and vegetables for free in a university canteen on the daily diet of university canteen customers. Canteen customers (n 209) were randomly allocated to a fruit and vegetable group (FVG) and a control group (CG). FVG participants were given two portions of fruits and one portion of vegetables for free at lunchtime. Food and beverage intake was measured using a dietary record for 3 d and dietary quality was appraised using a comprehensive scoring system. The FVG participants ate 80 g more fruits (P < 0·01) and 108 g more vegetables (P < 0·001) on a daily basis compared with the CG participants. No differences were found for energy density, total energy, Na and energy from fat between the groups per day. A higher intake of fruits and vegetables was observed at lunch and of vegetables during the dinner and evening snacks. The FVG participants were more likely to comply with dietary recommendations for fruits and vegetables and had a better dietary profile on the study days and for the lunch consumed on those days. The results of the present study demonstrate how modifications of a canteen lunch can be instrumental to enhance the nutritional quality of lunch as well as the overall quality of the diet of the customers.