The legal problem concerning consequences of determining the unfairness of standardized contractual terms and further the ineffectiveness of the whole contract is becoming more and more important issue in the days of growing number of cases which are questioning the legal validity of the loans indexed to the CHF. The Supreme Court ruling of 19 September 2023, II CSKP 1627/22 rescinded so far interpretation concerning unfairness control of standardized terms included in the loans by narrowing transparency requirement and thus far possibility to control clauses of the main subject matter. The subject of the article deals with direct critic of such ruling which is based on the presentation of transparency requirement created on the basis of directive 93/13/EEC, goals which are set to achieve by that regulation and minimal directive implementation requirement which has to be taken into account when interpreting polish law. The main effect is interpretational guideline to understand transparency requirement broadly, as it encompasses variety of non-transparent caluses. It also analyzes the linguistic understanding of transparency with reference to such aspect as clarity, unequivocalness and understandability. Legal arguments in this matter are based mainly on the doctrine developed in UE consumer law and Polish and German civil law. They are focused on presenting the preferred direction of UE countries domestic legislation which is obliged to ensure the full effectiveness of the directive 93/13/EEC. As long as directive opens the general possibility to wide interpretation of transparency requirement it is to be determined what specific non-transparent clause would be deemed as unfair and in conclusion ineffective.