The aim of this study is to investigate 32 master's and 16 doctoral theses in the Higher Education Thesis Center (http://tez2.yok.gov.tr/), which were conducted between 2008 and 2022 in science education and which are about inquiry-based learning approach, by content analysis method. The data obtained through document analysis were analyzed by content analysis. In addition, it was aimed to identify the frame on inquiry-based learning in science education and to identify deficiencies and orientations. Document analysis method was used in the study. "Science Education Thesis Classification Form" was created by the researchers by examining the categories and themes created in the content analysis studies in the literature. Theses were accessed by searching the words "inquiry-based" and "inquiry-based learning" on the Council of Higher Education Thesis Center. Theses were examined in the categories of thesis type, year of publication, research method of the thesis, research model type of the thesis, sample size of the thesis, sample level of the thesis, data collection tool of the thesis and data analysis method types of the thesis. The data obtained were calculated with MS-Excel program. The analyzed postgraduate theses were evaluated separately as master's and doctoral theses. Frequency and percentage values were given in tables. As a result of the research, it was concluded that while the majority of the theses examined were master's theses, the theses conducted within the scope of doctorate were much less; quantitative research model was preferred more in the studies, and the most studies were conducted in 2019. It was found that undergraduate students were selected as the sample in the majority of the theses within the scope of the study; fewer studies were conducted at the primary education level, and the range of 51-100 was the most preferred number in sample size. At the end of the study, suggestions were made for future studies.