In this study, pre-service primary school teachers’ problem solving processes is researchedaccording to Polya’s problem solving stages. The research had been realized qualitatively as a casestudy with 62 participants studying at third grade of primary school teaching department of astate university’s faculty of education. Participants had information about Polya’s problem solvingstages in Mathematics Teaching course, solved several routine and non-routine problems andevaluated them. At the end of the five-week period, the pre-service teachers were given a nonroutine problem and were asked to solve the problem individually taking these stages intoaccount. Subsequently, the solution processes were analyzed descriptively in the light of thesestages. At the end of the research, it was obtained that most of the pre-service teachers correctlyapplied the stages which are understanding the problem, devising a plan and carrying out the planin the problem solving process. It was determined that most of them specified and applieddifferent strategies such as systematic listing, guessing and checking, reasoning in order to solvethe problem, and some others applied a different strategy than the ones specified. Moreover, theevaluation phase of the solution has been either ignored or incompletely implemented by some ofthe pre-service teachers.