Abstract The article discusses the problem of ensuring a high level of software reliability. A software reliability high level can be ensured using N-version programming. N-version software is distinguished by the software components redundancy, designed to solve one problem using different methods. Software redundancy requires additional resources. The challenge is thus to increase the software reliability, while at the same time minimising the resources used. In this article, ant colony optimization is used to solve the problem of choosing the optimal set of versions of N-version software.