The master thesis presents reliability methods which are used in engineering to assess the reliability of structures, and their application to several geotechnical problems. The first part of the paper reviews soil variability, which is one of the main causes of uncertainty in geotechnical analyses. In reliability analyses, geotechnical parameters are treated as random variables, which requires knowledge of data on their statistical characteristics. In this way, uncertainties arising from different sources are taken into account, such as natural soil variability, errors of transformation models and the like. For most geotechnical parameters in the literature, data on their statistical distributions, typical means and coefficients of variation are available, which allows the implementation of reliability analyses in case of insufficient data from the results of research. The issue of soil variability and its impact on the results of geotechnical analyzes is also recognized in the Eurocode standard, so the paper gives an overview of that.. The notion of reliability index, which is used as a measure of structural reliability, is described. In addition, its application is possible for the calibration of partial factors of action, materials and resistance prescribed in the Eurocode standard. Two reliability methods are described and applied in the paper, the FORM analytical method and the Monte Carlo simulation method. A series of reliability analyses with variations of geometric characteristics and coefficients of variation of dominant geotechnical parameters were performed. For selected geotechnical problems, the convergence of the Monte Carlo method, the error of the FORM method, and the influence of the coefficient of variation on the magnitude of the reliability index were analysed. All the analyses which are presented in the thesis were conducted by using the Python programming language and the Pystra open source library. It can be concluded that in all considered examples the FORM method had satisfactory accuracy, and that the coefficient of variation had a significant impact on the reliability index, which is why it is necessary to pay special attention when determining its value.