The UN Sales Law (CISG) is applicable law in many important trading nations. It automatically applies when the conditions for application defined in the convention text are met, including when the parties to a sales contract are established in different contracting states. Despite the advantages of this unified sales law, its applicability is often excluded. This work addresses both the general requirements for the exclusion of the convention and the issues that arise in the case of an explicit or implicit exclusion. Furthermore, the results of a survey conducted by the author in the USA and Germany are presented. The survey focused on how often, in what ways, and for what reasons the application of UN Sales Law is excluded.