This article, presents empirical evidence supporting instability of the Phillips curve in Turkey. We employ the multiple structural break models and the Markov-switching models and then evaluate the performance of the two models. The data pertain to the monthly inflation rate in Turkey for the period of 1987 to 2004. The results show that the Turkish Phillips curve is not linear. There exists no evidence on the asymmetry in the inflation response to output gap. The persistence of inflation is found to be much lower than in linear models. After 2001, slight decline in persistence of inflation is observed. There exits weaker support for the Phillips curve for the periods where the policymakers attempt to take the advantage of the tradeoff between output and inflation relationship.