The aim of this study was to determine preservice mathematics teachers' personal figural concepts and hierarchical classifications about quadrilaterals and to investigate the relationships between them. The participants were 57 preservice primary mathematics teachers in their senior year at a state university in Turkey. The preservice mathematics teachers were administered a questionnaire that consisted of 13 questions extracted from studies on the descriptions and images of quadrilaterals, identification of quadrilateral families among given images, and identification and classification of the relationships between quadrilaterals. The results showed that the preservice mathematics teachers' knowledge of quadrilaterals learnt at primary-secondary school level and prototypical images were dominant in their personal figural concepts. Also, the teachers didn't use the hierarchical definitions of quadrilaterals and were not able to establish relationships among quadrilaterals due to the effect of prototypical images in choosing a family category among the given images. On the other hand, the majority of the participants gave correct answers to the questions about the dual relationships among quadrilaterals. The study concluded that although the preservice teachers possessed formal definitions of quadrilaterals, their prototypical images affected their personal figural concepts.