The lobbying is a sensitive subject in Switzerland. But while many critics are aimed at the lobbyist themselves, this book investigates the other side of lobbying, namely the parliamentarians. This thesis follows two goals, firstly it runs a quantitative and qualitative analysis of the economic ties of Swiss parliamentarians. The objectif of these analysis is to prove the existence of a correlation between the number of economic interests and the political inclination of a parliamentarian. Secondly it tests the partisan theory's assumption: the farther right a member of parliament is, the more economic ties he will have.