Even though there is a lot of research both on formative assessment and structural knowledge, the formative assessment of structural knowledge is an absent element in the study process. One tool which could be used successfully by teachers for the mentioned purpose is concept mapping. However, its application for formative assessment is rarely based on a well-planned approach. This paper presents results indicating that concept mapping is a suitable tool for the formative assessment of structural knowledge. It is the first step of the development of an approach for the use of concept mapping in the formative assessment of structural knowledge. This paper is based on a) extensive analysis of available information sources on formative assessment and concept mapping and b) reflection of the author’s personal experience of implementation of formative assessment activities using concept mapping. The goal of the paper is not only to justify usage of concept mapping as a tool for the formative assessment of structural knowledge, but also to encourage teachers to use concept mapping in their practice for formative assessment purposes. This paper briefly describes elements of concept maps, defines the concept of structural knowledge and discusses the process of formative assessment. Suitability of concept mapping for the formative assessment of structural knowledge is considered in the light of three questions: Do concept maps allow seeing clearly differences between experts’ and novices’ structural knowledge? Does concept mapping support the main aspects of formative assessment? Is it possible to minimise the cost of formative assessment based on concept mapping?