The electoral systems play a key role in transforming the votes into parliamentary seats. Therefore, a change in the electoral system will also affect the parliamentary composition. The aim of this study is to document the effect of "Electoral Alliance System", which was first used in 24th June 2018 General Parliamentary Election in Turkey, on the seat share of the parties in the parliament. The impact is measured by converting the votes used in the electoral districts into the electoral system prior to Law No. 7102 in 2018 (countrywide threshold / non-allied d'Hondt) and comparing the data obtained with the current composition.