Abstract Objectives To determine the nutritional adequacy and acceptability to children of vegetarian lunches served on ‘Thursday Veggie Day’ – a public health initiative in Ghent (Belgium) primary schools. Design A comparison of food leftovers from main courses on regular days and Thursdays was made using a visual plate waste method. The nutritional value of the vegetarian meat analogue and meat components of main courses served on five ‘Thursday Veggie Days’ and five comparable conventional main courses was evaluated using three criteria (maximum 30 % of energy from fat, maximum of one-third of fat as saturated fat and minimum 1·5 g of dietary fibre per 420 kJ). Setting Two canteens from primary schools in Ghent, Belgium, participating in the ‘Thursday Veggie Day’ campaign. Subjects Primary-school children aged between 6 and 12 years. Results In total, 1242 and 472 main course plate waste observations of conventional and vegetarian menus, respectively, were evaluated. There was no significant difference in plate waste between vegetarian (16·7 %) and conventional (17·3 %) main courses. Overall, the five vegetarian components were found to be nutritionally adequate with a mean score of 2·2 out of 3, compared with 0·4 for the meat component. However, three of the vegetarian components provided >30 % of energy from fat and, in one, the amount of saturated fat exceeded one-third of total fat. Conclusions Vegetarian canteen meals offered as part of ‘Thursday Veggie Day’ appear to be nutritionally appropriate and as acceptable as conventional main courses to children in primary schools in Ghent.