The prevalence of temporomandibular disorder (TMD) in the general population is difficult to identify. Depending on the source, values range from 3% to 48.9%. These large discrepancies occur because of two main reasons. The first one is connected with the evolution of the definition and diagnostic criteria of TMD, while the second one concerns the use of different diagnostic tools, protocols, etc. Temporomandibular joint (TMJ) diagnosis is both quantitative and qualitative. Quantitative measurements used in the field of scientific research are highly accurate motion capture systems used for kinematic analysis, while an electronic caliper is applied in a clinical setting. MRI seems optimal in TMJ disc and its dysfunction imaging. In more difficult cases, ultrasound imaging can be used. On the other hand, CT is the best examination for joint imaging. In recent years, qualitative measurements have been dominated by vibroarthrography (VAG), which shows good diagnostic value. Research Diagnostic Criteria for Temporomandibular Joint Disorders (RDC/TMD) is the most complex systematized diagnostic tool for TMD. The proposed procedure allows us to differentiate a real TMJ dysfunction from other systemic problems that can manifest themselves in this region of TMJ, such as depression, chronic pain or psychosomatic disorders. RDC/TMD are constantly evaluated and modified in terms of their diagnostic or clinical value by experts associated in the International RDC-TMD Consortium. Currently it is the best tool available for TMD diagnostics. The RDC/TMD questionnaire was translated into Polish, culturally adapted and officially approved by the Consortium. The aim of the study is to review selected TMD diagnostic tools and to assess their diagnostic value.