In the context of his scientific activity, apart from a large number of scientific conferences, in which he attended and read presentations, Zizioulas gave lectures by invitation at the following Universities:

a) University of Helsinki, Finland (1969)
b) University of Turku, Finland (1971)
c) University of Strasbourg (1971)
d) University of Louvain (1981)
e) Ecumenical Institute Bossey, Switzerland (University of Geneva) from 1968-1980 every year.