Inferior joint space arthrographies for the 37 patients with internal derangements of temporomandibular joint or joints were examined clinically. All arthrograms showed various problems of postural and morphological findings of the disc. Clinical diagnosis for the existence of internal derangements of the temporomandibular joint was completely confirmed by lower joint space arthrography. It must be considered, however, that clinical diagnosis for the morphological changes of the disc associated with internal derangements of temporomandibular joint is difficult. Inferior joint space arthrography was very useful to evaluate optically the discal formation in the cases.