Mrs. Vardinoyannis co-operates with several NGOs around the world, such as: Fondation pour l`Enfance (France), AVEC (France), International Peace Bureau (Switzerland), Hague Appeal for Peace, Jordan River Foundation (Jordan), Robert F. Kennedy Human Rights (USA), Heydar Aliyev Foundation (Azerbaijan), Qatar Foundation (Qatar) and others. She participated in many international and European meetings, such as:
- The first ECPAT World Congress on Sexual Exploitation of Children, in Stockholm, which was held under the auspices of H.M. Queen Silvia of Sweden (August, 1996)
- The Summit of the “Fondation pour l’Enfance” in Paris, for the presentation of the work of the “European Office for Missing and Exploited Children”. She participated as a keynote speaker (November 1997)
- The International Conference on Missing Children organised by INTERPOL and the “Fondation pour l’Enfance”,