This study uses an ARDL(p, q)-model to express a long-run relationship between ‘Stockholm Interbank Offered Rate Tomorrow/Next’ and the inflation in Sweden between 2007 and 2016 to see how efficient the ‘interest rate-weapon’ as a monetary policy-tool have been in affecting the inflation. The study shows that no such relationship can be expressed – hence the conclusion that the expectations of inflation are the most important variable affecting the inflation, and that the agents in the Swedish economy have rational expectations and a trust in the central bank of Sweden to reach its target of a 2 percent inflation rate.