Confidentiality is one of the most controversial topics in international commercial arbitration. Most inexperienced users simply presume that the arbitration proceedings are confidential. Those with more experience realize that this is not simply a black-and-white issue, and in the absence of an express agreement and specific regulation, confidentiality will not be guaranteed. Given the multitude of sources, it is not easy to determine whether the relevant person is bound by the confidentiality obligations regarding the documents or information related to the arbitration proceedings. It is therefore essential to identify the relevant sources. The subject matter of this article is limited to examination of such sources as an express agreement, international arbitration rules, generally accepted arbitral practice, national case law, and legislation. Based on this analysis, it becomes clear that the involved parties’ autonomy regarding the existence and scope of confidentiality of the arbitral proceedings is very important. For the parties seeking some predictability, it is therefore advisable to conclude an express agreement, as well as to carefully choose the seat of the arbitration, the law applicable to the contract, the applicable procedural rules, and the institutional arbitration rules.