The aim of the study is to find out the problem-solving strategies used by primary school 3rd and 4th-graders in solving non-routine problems. The basic qualitative research design, one of the qualitative research approaches, was used in the research. The participants of the research consisted of 216 students, 104 of them in the third-grade and 112 of them in the fourth-grade. The "problem-solving test" developed by the researcher was used as a data collection tool. Descriptive analysis method was used in the analysis of the data. When the results of the research were examined, it was discovered that primary school third-graders mostly used making a drawing strategy in solving non-routine problems; guessing and checking and looking for a pattern strategies were the most commonly used strategies after making a drawing strategy. When the problem-solving strategies used by primary school fourth-graders were examined, it was discovered that guessing and checking was the most commonly used strategy and this strategy was followed by the strategy of looking for a pattern and making a drawing. It was concluded that primary school fourth-graders were more likely to use the other problem-solving strategies apart from making a drawing strategy than the third-graders.