In this study it was aimed to determine pre-service primary teachers' knowledge structures of fraction through problem posing activities. A total of 90 pre-service primary teachers participated in this study. A problem posing test consisting of two questions was used and the participants were asked to generate as many as problems based on the following conditions: i) using both 1/2 and 3/4 fractions, and ii) using either 1/2 or 3/4 fractions. Data were analyzed using both semantic and constant comparative analysis techniques. The results of the study showed that there was substantial diversity in the problems posed by pre-service primary teachers. Moreover, participants preferred to pose story and symbolic equations in first task and story equation in second task. Furthermore, the participants faced some issues such as not realizing 1/2 + 3/4 situation is more than 1, missing data, choosing wrong number, using different fractions and posing non-fraction problem.