Mitral valve diseases are usually asymptomatic and are most often discovered accidentally. Over time, they burden the heart chambers and change their structure and function. The most important method in the diagnosis and evaluation of the degree of the disease is echocardiography. To date, a number of mitral valve repair techniques have been developed. In order to select the most appropriate method for the patient, it is necessary to use the Functional Classification and carefully analyze the valve intraoperatively. With the development and improvement of various mitral valve repair techniques, there are also growing dilemmas. Many studies have tried to compare chordal replacement and resection techniques, but no data have yet been obtained on some significant differences or advantages of a single technique. In this retrospective study, we studied 53 patients who were admitted and treated at the Department of Cardiac Surgery of the Clinical Hospital Center (CHC) Rijeka in the period from September 2011 to September 2019. One group underwent resection techniques to repair the mitral valve, and the other underwent chordal replacement. Most of the results correspond to the results of previous research and the most significant result was observed with the size of the implanted prosthetic rings.