The principle of relative effect of the contract with regards to third parties is presented as a limit and also a guarantee of freedom of contract.The direct effects are only those created by the stipulation in favour of third parties. The indirect effects are, on the one hand, those effects on third parties which result from the legal activity of another. English law reflects the principle of relative effect of contracts in the Doctrine of Privity of Contract. The aim of this paper is to show how this principle finds placein Community law and in national law. European law is centred on the protection of third parties to the contract constituting the company. In the Unidroit Principles, the principle only appears from an a contrario.In some legal systems, the effect ofthe contract with regard to third parties is particularly strongly regulated. In others it is only through the sanctioning of the violation of third party rights that these effects are taken into account.Within the Common law systems, it is generally admitted that the contract only produces effects between the parties, and the situation of third parties is rarely studied. The approach is different once again in those systems that are today essentially still based on Roman law.