This is a retrospective study of 31 patients, who were diagnosed as bilateral TMJ internal derangement in consequence of magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) at Department of Dentistry, Ajou University Hospital, and who were compared clinical findings with radiological findings. The results obtained were as follows. 1. The average of the patients of bilateral TMJ internal derangement was 27.3 years with a range from 12 to 74 years, and 93.6% of the patients were yonger than 40 years of age. The male-female ratio was 1 : 6.8, and the females of $20{sim}29$ years were most common in 35.5%. 2. In the patients of bilateral TMJ internal derangement, the patients who complained clinical symptoms bilaterally were 38.7% and the patients who complained clinical symptoms untilaterally were 61.3%. 3. The most common disc position of bilateral TMJ internal derangement was anterior disc displacement without reduction on both sides in 38.7%. The most common disc configuration of bilateral TMJ internal derangement was biconcave on both sides and amorphous on both sides in closed mouth, and was amorphous on both sides in open mouth. 4. In the patients of bilateral TMJ internal derangement, the joints which really showed clinical symptoms were most common in anterior displacement without reduction of 48.9%.