The book examines the legal nature, types, procedure for approval and appeal of so-called extraordinary transactions - major transactions, interested party transactions, as well as transactions for which a special approval procedure is provided for by the charter of a business company. The author, among other things, analyzes the changes coming into force on January 1, 2017, introduced into corporate legislation by the Federal Law of July 3, 2016 No. 343-FZ “On Amendments to the Federal Law “On Joint-Stock Companies” and the Federal Law “On Companies with limited liability" in terms of regulation of large transactions and transactions in which there is an interest", which significantly reformed the legal regime for carrying out large transactions and interested party transactions (grounds for qualification, procedure for internal corporate approval, grounds for protecting the rights of participants in corporate relations when carrying out these transactions). The book is intended for the widest range of readers involved in corporate law - practicing lawyers, corporate secretaries, the judicial community, researchers, graduate students, students studying in legal and economic fields.