The paper examines some current issues of challenging debtor’s related transactions under the rules of bankruptcy legislation. The author concludes that related transactions are characterized by formal differentiation but substantive unity. The paper proposes a classification of related transactions depending on their structure into co-directional, multi-directional and chain transactions. The first type is characterized by a common subject and a coinciding parties involved and give rise to a single legal relationship. Multidirectional transactions are united by a common goal, but involve the participation of several independent entities and a different subject matter. A chain of transactions is a set of consecutive transactions with the same subject matter that covers the same transaction. It is concluded that when challenging the debtor’s transactions under the rules of the Bankruptcy Law, it is necessary to evaluate not only each individual transaction, but also related transactions, to consider them in unity and interrelation. This will make it possible to determine their actual property consequences for the debtor and the bankruptcy assets, since otherwise the rights of both the debtor’s counterparties and creditors may be violated.