The article concerns selected issues regarding smart contracts from the perspective of private law, in particular the concept of a contract, determination of its content, principles of performance and breach of an obligation. The legal analysis jest supplemented with technological aspects that show the essence and mechanism of operation of Blockchain, smart contracts, Ethereum. The legal doctrine generally referred to the technological aspects of smart contracts, attempting to include them in the traditional contract law system. The article contends that this is the wrong approach. The authors argue that a smart contract as such is not a contract, but a computer program (code) that can be a manner of concluding a contract and at the same time self-executing it. The qualification of a smart contract as a method of conclusion a contract, and not the contract itself, determines the conclusions on other aspects of concluding the contract, its interpretation, etc. Considerations concerning the model of a self-executing contract are formulated around this thesis. This model determines the proposals for regulation of the principles of performance of the contract, the consequences of the breach of contract and others areas of concern.