Unilateral condylar hyperactivity is a growth disorder which is characterised by a progressive asymmetry in the mandibula and in some cases also secondarily in the maxilla. Various forms are hemimandibular hyperplasia, hemimandibular elongation and a hybridform. In deciding on a plan of treatment, it is important to determine whether there is a question of continuous and/or excessive condylar activity, possibly with the help of a skeletal scintigraphy.