Cervical external root resorption is a progressive resorption process occurring at the site of the attached gingiva. It is independent on the condition of the pulp. Prerequisites for its occurrence are a damaged root surface and the presence of vascularized connective tissue. The specific stimulus for the resorption to start is still unknown. In most cases the resorption process is without clinical symptoms; diagnosis is made on radiographs. The prognosis of teeth with cervical external root resorption is low: at the time of screening too much tooth material has often been resorbed to be able to make a restoration. Only limited resorption areas with good surgical accessibility may be successfully treated. Thus, of prime importance is an early screening of the resorption process. Therefore, in interpreting radiographs one should not only look for carious or periodontal decay, but also for areas indicative for cervical external root resorption. Complete radiographs are to be advised in order to screen for possible other resorption sites.