This paper deals with the topic of preferential voting in Slovak parliamentary elections by means of a comparison with the model applied in the Czech Republic. The aim of the article is to point out the main features and weaknesses of the Slovak model. It shows that the low effectiveness of the Slovak system lies in the existence of a nationwide electoral district composed of 150 seats. In the end the author suggests possible solutions to this problem, including a way for lower ranked candidates to use the weak point of the current system for their own benefit