This dissertation aims to analyze the double function of the sole paragraph of article 473 of the Civil Code: (i) ensure the termination by notice is made after the fulfillment of a minimum period of the contract, allowing its satisfactory performance and the amortization of the investments made by the reported party, and (ii) ensure the reported party is notified early enough to take action in order to prepare for the termination of the contract. In view of the interests that the sole paragraph of article 473 of the Civil Code aims to protect we intend to verify whether the aforementioned legal provision should result in the compulsory maintenance of the contract or the payment of compensation for material damages, and which damages should be compensated. To that end, we initially analyze the unilateral termination, foreseen in the caption of article 473 of the Civil Code, as a potestative right, distinguishing it from dissolution, contract cancellation and termination by notice. Also examined are the hypotheses in which the law allows unilateral termination and the possibility of the parties contractually establishing the termination by claim of the contract upon prior notice or payment of a fine. Then, objective good faith is examined as a criterion for assessing the abusiveness of the termination by notice; the duty of prior notice; the function of the stabilizing period; and the criteria for setting a reasonable period. Finally, the third chapter deals with the remedies for unilateral termination of the contract - namely, the specific performance of the obligation and the payment of compensation for material damages - and the damages to be compensated.