This article is devoted to the analysis of application of different procedural consequences of filing with a court of a plea as to arbitral jurisdiction based on the arbitration agreement by commercial courts of all levels. The author reached a conclusion that sometimes commercial courts terminated proceedings with reference to article 80 (1) (1) of the Commercial Procedural Code of Ukraine («the dispute is not subject to commercial courts of Ukraine») and sometimes with reference to paragraph 5 of the said article («parties entered into an agreement on the reference of the dispute to an arbitration court») in the same factual circumstances: an arbitration agreement was included in a contract. The research in the Unified Register of Court Judgements gave the author grounds to identify two more categories of violations: sometimes courts refused to accept a claim in cases where parties entered into an arbitration agreement with reference to article 62 (1) (1) of the Commercial Procedural Code of Ukraine or even considered cases in erroneous belief that arbitration agreement does not preclude them from considering merits. O. Frolov identified a reason of such situation and offered a way out by introducing amendments to the Civil and Commercial Procedure Codes of Ukraine as well as to recommendatory acts of the High Commercial Court of Ukraine. The author also reached a conclusion on certain critical defects of the existing procedural model of referring parties to arbitration, which may give rise to the situations where a claimant cannot exercise its procedural rights in arbitration or court of law, among others, due to the fact that arbitral agreement is not enforceable.