Opinion surveys in Slovenia have shown low levels of trust in political institutions during the recent years, especially low levels of trust in political parties. Levels of trust in political parties in correlated with voters turn out at the parliamentarian elections. In the master thesis, we first focus on the process of establishment of political parties in general and specifically in Slovenia. A detailed analysis of parliamentary elections in Slovenia in 2008, in 2011 in 2014 shows that newly established political parties in Slovenia are entering the parliament. The success of newcomers is compared with the success of newcomers in selected countries: Estonia, the Czech Republic, Poland and Hungary. The success of new political parties depends on several factors, the most important ones are electoral system and the electoral threshold. Slovenia has an electoral system that is friendly to new political parties, also the threshold is low and it shows that Slovenia is in comparison to selected countries, a country with the highest number of new political parties that entered the parliament.