The distal radioulnar joint (DRUJ) plays a tremendous role regarding the functionality of the upper extremity. Lesions of the DRUJ can limit the functionality of the upper extremity decisively. Many clinical and radiological procedures are used to diagnose instability of the DRUJ. Up to now, there has not been a general consensus concerning the standardisation of the evaluation of DRUJ instability. The TFCC (triangular fibrocartilage complex) with its ligamentum subcruentum insertions at the fovea ulnaris and at the basis of the processus styloideus ulnae is in conjunction with the membrana interossea a very important stabiliser of the DRUJ. A fall on the extended hand or a forceful wrist rotation can usually cause injuries to the stabilisers. Ulnar-sided pain, limited pronosupination and loss of grip strength are clinically apparent. Both clinical tests and radiological procedures should be judged regarding their specific efficacies. These tests have to be evaluated in comparison to the gold standard of wrist arthroscopy. Each test alone is not able to verify DRUJ instability on a regular basis. The introduction of a standardised diagnostic procedure including anamnesis and specific clinical and radiological tests should be established. The standardisation ought to be maintained strictly in order to guarantee a growing test efficacy. Finally, high diagnostic reliability is based on a thorough examination which includes complementary clinical and radiological procedures.