Abstract. We give conditions on the subgroups of the circle to be realized as the subgroups of eigenvalues of minimal Cantor systems belonging to a determined strong orbit equivalence class. Actually, the additive group of continuous eigenvalues E(X, T ) of the minimal Cantor system (X, T ) is a subgroup of the intersection I(X, T ) of all the images of the dimension group by its traces. We show, whenever the infinitesimal subgroup of the dimension group associated to (X, T ) is trivial, the quotient group I(X, T )/E(X, T ) is torsion free. We give examples with non trivial infinitesimal subgroups where this property fails. We also provide some realization results.