Due to its specificity, the legal institute of preliminary agreement poses a number of questions. This pre-contractual agreement is not yet a contract. Therefore, the form and scope of legal protection will not be the same as that guaranteed to contracting parties. However, the European legal systems would claim that the relationships between the parties during pre-contractual negotiations have to be regulated and protected by the law. The first part of this article deals with the legal nature of pre-contractual liability: (...) tort, contractual or sui generis. The question of determining the type of applicable civil liability for breach of a preliminary agreement still remains a matter under debate in the Lithuanian legal doctrine as well as in legal practice. Taking into account the specific interest that may be infringed and the fact that the aggrieved party cannot recover the expectations it had in profit of the sought contract, including the remedy of the right of performance, there is nosufficient reason to apply contractual legal regime for breach of the preliminary agreement either. Hence, the special nature of the pre-contractual phase merits special treatment. In the Lithuanian legal system, liability for breach of a preliminary agreement should therefore be qualified as a separate sui generis kind of liability. In fact, the biggest problem is the scope of damages recoverable under the preliminary agreement. As far as the tendencies of a legal doctrine and jurisprudence of Lithuania and other countries are concerned, the aggrieved party should be compensated not only the direct expenses incurred during the negotiations, but also the value of lost opportunity, which must be based on real, proven, unavoidable income or expenses. It is not possible to claim the profit which would have resulted had the main contract been concluded (the so-called expectation damages). Recent tendencies show that the Lithuanian courts are prone to make no distinction between the concept of the lost opportunity to conclude a transaction with a third party (as reliance damages) and lost profits as expectation damages. The reason for such an interpretation is the fact that the value of lost opportunity can be determined by applying the principle of price difference provided in Article 6.258(5) of the Lithuanian Civil Code, which is used for contractual liability. This principle should be applied in accordance with the Commentary on the UNIDROIT Principles of International Commercial Contracts and in the context of the nature of the preliminary agreement. Therefore, the aggrieved party may claim compensation for damages in the amount of difference between the price of the contract that has not been concluded with a third party and the price of the replacement contract. Such an interpretation reflects the compensatory function of the recovery of the value of the lost opportunity. (shrink)