The paper discusses the relation between inflation and participation in the exchange rate mechanism ERM II which is necessary for the euro adoption. The first part is focused on the level of the real and nominal convergence and its relation to the level of inflation. Especially on possible ways of price levels equation of new member states of the European Union or euro area with the old ones. It is theoreticaly based on the Optimum currency area theory, the theory od growth and the theory of the economic cycle. In the next part, the focus of attention is the development of infaltion in states participating in the exchande rate mechanism ERM II - Slovakia, Denmark, Lithuania, Latvia and Estonia and those which alredy letf it and adopted euro - Slovenia, Malta and Cyprus. The second subject of attention is the development of exchange rates of their currencies during the period of ERM II participating and before it. The final part is targeted the possible connection between develoment of inflation and exchange rate in states participating in the ERM II mechanism. Using correlation and regression analysis I also discus potential connection between development of inflation in these states and in the whole European union and euro area.