Background: Several school-based fruit and vegetable interventions include activities to involve parents, but not much is know about the effectiveness of such a family component on child and parent intake levels. The current study evaluated the effects of the multi-component school-based intervention, 'the Pro Children Study', on mothers' intake levels. Furthermore, associations between level of involvement in the project and improvement in the mothers' intake levels were assessed. Methods: Effect was evaluated in a cluster randomized controlled trial in Spain, Norway and the Netherlands among mothers of 11-year-olds. Of the 1253 mothers with complete data at baseline, 754 and 476 had complete data at first and second follow-up respectively. Fruit and vegetable intake, level of involvement and demographic variables were assessed by a parental questionnaire. Data was analyzed using multilevel regression analyses. Results: Results showed no effect of the intervention on mothers' fruit and vegetable intake after one year and two year follow-up. Participation rate for the different activities varied by activity and by country, e.g. 3.7-9.4% visited the website, while 26.4-72.6% of the mothers participated in the home work assignments. Results further showed that higher involvement levels were associated with higher intake at follow-up. Conclusion: The Pro Children Intervention could not increase the fruit and vegetable consumption of the mothers of participating pupils, which might be explained by the low involvement in the project. More research is needed to increase mothers' involvement in school-based interventions.