The right of retention is a construction that has become extremely popular recently, especially in Swiss franc loan disputes. However, a closer analysis leads to the conclusion that this construction raises several difficulties in interpretation. Particular doubts are raised by the assessment of whether a loan contract is a mutual contract because only in the event of invalidity of the contract is it permissible to invoke the right of retention. Another unclear issue concerns whether the right of retention can protect a claim that is not due. The possibility of invoking the right of retention when the entitled party is also entitled to the objection of set-off raises great doubts. Finally, it is necessary to clarify whether the possibility of submitting a declaration of exercising the right of retention does not violate the protection of the consumer resulting from the provisions on unfair contractual provisions.