This paper studies how Slovakia’s adoption of the euro in 2009 affected the structural macroeconomic relationships governing inflation, output, and monetary policy. We estimate a two-country structural VAR for Slovakia and the rest of the euro area, allowing for regime-specific contemporaneous interactions while keeping lag dynamics comparable across regimes. We find that euro adoption led to a pronounced flattening of the Slovak Phillips curve and a decline in the inflation sensitivity of aggregate demand, substantially reducing the inflation-output trade-off. Post-euro, Slovak supply and demand relationships become quantitatively similar to those of the euro area. These results suggest that monetary integration can induce genuine structural convergence in small open economies, reflecting changes in nominal anchoring and real economic integration beyond the mechanical loss of an independent monetary policy.