Nowadays concept maps as a pedagogical tool have stable positions in education because they are used for teaching, learning and knowledge assessment. The paper gives the basic conceptions of concept maps and their usage for knowledge assessment. The concept map based multiagent adaptive intelligent knowledge assessment system (IKAS) is described from the systems and interior structure’s viewpoint. The kernel of the IKAS is the intelligent knowledge assessment agent consisting of the agent-expert, the communication agent, the knowledge evaluation agent and the interaction registering agent. The knowledge assessment agent using the comparison algorithm based on graph patterns compares a teacher’s and a learner’s concept maps and assigns score for submitted solution. Five years experience of the IKAS practical use along with student feedback gathered in questionnaires is the driving force for extension of the functionality of the system. The paper presents student opinion about concept maps as knowledge assessment tool confirming that concept maps help systematization of knowledge and construction of its structure, and promote logical thinking. Evaluation results of four prototypes of the system used for knowledge assessment in different study courses are described. Evolution of the IKAS is reflected and its characteristics are summarized.