In this master’s thesis is described the Lee-Carter’s model for the projection of the mortality. The preliminary part describes actuarial notation necessary to understand the model and the methods that are used during the estimation of the parameters of the model. Mentioned methods are decomposition of the singular values, ARIMA model of time series and Newton-Raphson method for solving non-linear equations. Lee-Carter’s model is described in detail with additional descriptions of the least squares method and Poisson’s maximum likelihood method used to estimate the parameters of the model. In order to gain better projections of mortality rates there is also given the description of the smoothing of the data and selection of the optimal time period in which data is being collected. There is also the description of the projection of the mortality itself. To get a better insight of the model there is described its comparison to the Cairns-Blake-Dowd’s model. There is also described the model’s extension. It applies to the addition of the cohort effect to the model that includes time and age components. To conclude, it is given the practical example of usage of the model on the Belgium population from the literature. There is also given short description of the implemented procedures of the Lee-Carter’s model in the programming tool R.