Abstract
The paper offers the analysis of the theoretical approaches to the problem of mistake in the law of contracts and its relevance for the nullification of the contracts. Author focuses on the several understandings of mistakes: mistake of delusion, mistake of combination of misbelief and misconception, mistake in social interactions etc. Further he evaluates the legal consequences and the practical application of the abovementioned theoretical concepts. Finally author analysis the draft projects related to the mistakes in the law of contacts and their legislative implementation.