Background: It has been suggested that TMJ effusion may represent an inflammatory response to a dysfunctional disc-condyle relationship. The purpose of the present study was to evaluate whether the status of the disc in the temporomandibular joint, as depicted in magnetic resonance (MR) images, is predictive of the presence of temporomandibular joint (TMJ) effusion. Methods: The relationship between disc displacement and TMJ effusion was analyzed in MR images of 154 TMJs in 77 patients complaining for pain and/or dysfunction in the TMJ area and referred from medical practitioners to specialist consultation. Logistic regression analysis was used to identify the significant correlation between presence/absence of joint effusion and disc displacement. Results: Significant correlation (P<0.01) between disc displacement and joint effusion was found. OR for all type of disc displacement was 3.1, and the odds that a joint had magnetic resonance imaging findings of effusion was greater for anterior disc displacement without reduction. Conclusions: The status of the disc could represent a factor involved in the development of temporomandibular joint oedema. However, these findings suggest that disc displacement may not be regarded as the dominant factor in defining the occurrence of TMJ effusion. Certain local or systemic conditions other than the disc-condyle relationship must be considered.