The aim of this study is to investigate the research trends in dissertations on PBL from 2002 to 2015 in Turkey. For this purpose, the master's and doctorate dissertations in the National Thesis Database of Council of Higher Education (CoHE) were selected for rigorous content analysis. The analysis was utilized to classify the type of study, the learning domains, research methods, research designs, research domains, subject groups, group sizes, length of treatments and data collection instruments. For analysis purposes, frequencies and percentages were calculated for each category. Additionally, the results obtained in these dissertations were examined and reported separately with regards to cognitive, affective and conative domains. According to analysis results; science is the most favorable learning domain, quantitative methodology is more utilized as compared to qualitative and quantitative methods, cognition and affect followed by cognition only are the mostly utilized research domains, subject groups are predominantly at elementary education level and secondly from teacher education, studies preferred to have a group size of 41-80, the treatments on PBL research last mostly four to six weeks, and finally majority of the studies use achievement tests and attitude scales as instruments of measurement.