The author of the article observes that the provisions of TEU and TFEU do not envisage any role for national parliaments in the procedure of withdrawing from the European Union. In Poland, such rights can be interpreted from internal legal order of the Republic of Poland, for example from the act on cooperation between the Council of Ministers and Sejm and Senate. Sejm and Senate can request bills concerning the UK leaving the European Union from the Council of Ministers. In case a revision treaty is concluded, the procedure of ratification involving the Polish Parliament will be necessary. Such ratification will be also needed in case a new mixed agreement with the United Kingdom is concluded.