A product of European integration less analyzed by scholars and less visible in the European Court of Justice (ECJ)’s case law, is that of transnational administrative acts. These are administrative acts which, by reason of the authority that adopted them, the scope of their effects, their addressee, and/or their decision-making process, are “in-between” at least two national legal orders. The scope of transnational administrative acts is limited to horizontal relationships. This contribution will draw up a typology of transnational administrative acts and, on the basis of this typology, will analyze the solutions developed to enforce judicial review . The question of judicial review of transnational administrative acts is complex, because the presence of one exogeneous element may disrupt the straightforward path toward the right of access to courts—as both the determination of the competent court and the scope of the review carried out by the court seized become uncertain.