The main subject of paper is entrance of Croatian countries in the Kingdom of SHS and situation in the first years of the Kingdom of SHS existance. Based on accompanying literature author presents several theses. First thesis is that the unification of the State SHS with Kingdom of Serbia did in the unfavorable way for the Croatian countries. In continuation of paper author explains proces of forming a government and struggle of Croatian political parties for the increasing the rights of the Croatian people and political equality. Then author describes socio-political life in the Croatian countries and argues the thesis about bad attitude of the government to Croatian people in economic, religious and cultural issues. On the end of paper author makes a concluding thesis which means that struggle of Croatian politicans for reorganization of the state on the principle of equality did not succeed, moreover, it ends in tragic way and as a result, it appears in certain Croatian politicans in emigration idea of revolutionary struggle for collapse of the Kingdom SHS/Kingdom of Yugoslavia and the emergence of independent Croatian country.