SUMMARY The goal of the present thesis is to ascertain patients functional classes changes of various time after surgery, investigation of the other factors, which may stipulate recovery state (alive or die) and to estimate investigation of other factors, which may stipulate survival time. The investigation was carried out in two stages. During the first stage, the data was accumulated for processing (investigation of the pairwise independence of variables); the second stage implied solution of the statistical tasks (solution of the tasks, which correspond to the goals of the thesis). The methods of data analysis, the model of binary logistic regression, the descriptive methods for survival data and regression model for survival data were applied. 120 patients, who survived the mitral valve incompetence, were investigated and it was ascertained that functional class depends on difficulty of disease. The Sign‘s and Wilcoxon‘s tests assisted us in drawing the conclusion that statistical significance of surgery produce an impact upon the functional class to the 6‘th month and from 2‘th year to the 6‘th year. The model of the binary logistic regression assisted us in drawing the conclusion that functional class, acute disease and operation time produce an impact upon recovery state (alive or die).