The Diploma thesis is focused on Community customs union and relations with third countries, regarding particularly customs procedure during foreign transit operations. It is aimed to summarize basic knowledge regarding TIR system operation with emphasis on its current development and modernization. At present, TIR regime is experiencing a very dynamic progress, and it is related both to its computerization and changes in the European Union, which tends to enhance safety standards on the international level when shipping the goods. Therefore, the means of communication are improved by the interconnection of main actors engaged in business transactions, such as national customs authorities and associations, traders and international organisa...