Authors have obserbed a rare case of unilateral hypertrophy occured in the left mandibular condyle of 25 years old man. In the serial roentenograms, Authors have drawn following conclusions. 1. The patients face is markedly asymmetrical. This asymmetry consisted of an elongation and widening of the left mandibular ramus, neck and head of condyle which pushed the chin to the other side. 2. Left mandibular angle is flattened and mandibular inferior border is lower than right. 3. In the relationship of the left posterior teeth, severe mesioocclusion is occured.