One of the important guarantees of the defendant’s rights in civil proceedings is the institution ofcounterclaim. The right to submit a counterclaim is the subjective right of a person who is broughtto trial by the court in accordance with the initial lawsuit. Despite the seemingly rather detailedregulation of the institution of counterclaim, in practice some issues remain unsolved. The articlesets out the question whether the defendant can use this means of protection of its rights in thecase of participation of the international intergovernmental organization as a plaintiff. This issue isvery important, in particular from the point of view of choosing the tactics of defense in the judicialprocess. Based on the analysis of international agreements, including those with the participationof Russia, the author comes to the conclusion that an international organization must be recognizedas renounced judicial immunity with respect to a counterclaim, directly related to the initial one,if this organization has sued to the Russian court. If there is a mutual connection, a counterclaimto an international organization must be considered together with the original claim, without anyadditional conditions, regardless of considerations of procedural economy. Consideration by a courtof a counterclaim to an international plaintiff organization within the framework of process that hasalready begun to a greater extent provides for convenient and timely protection of the defendant’srights as an equal party, rather than consideration of his claim to the other participant in anotherindependent case. In this case, a counterclaim is a kind of protection against the judicial immunityof an international organization. In the author’s opinion, the international organization should alsobe considered as renounced judicial immunity in respect of the original claim, if the organizationfiled a counterclaim in the Russian court. In these cases, the renouncement of the right to judicialimmunity is characterized by the conclusive procedural actions of the international organization andis expressed in the choice of a certain line of conduct, excluding other legal protection mechanismsin order to avoid the abuse of the right.