A radiographic method expressing the alveolar bone level in absolute figures is presented. By means of a calibrated measuring radiographic film fixed to a magnifying viewer, alveolar bone levels were determined directly on intraoral periodic "identical" radiographs. A polyether impression was made for fixation of the filmholder in order to obtain reproducible radiographs. The method was applied to assess changes in the alveolar bone level at endosseous implants and abutment teeth. Radiographs of 23 endosseous implants and 21 abutment teeth from nine patients were examined and measurements of the alveolar bone level were performed. The mean difference between double observations on the same exposure as well as on repeated exposures was about 0.2 mm (s.d. 0.17-0.32 mm). The uncertainty of the present radiographic method was mainly due to the measurement procedure, as the radiographic technique showed a high degree of reproducibility. The method is a simple and reliable technique for longitudinal investigations of changes in the alveolar bone level at endosseous implant and tooth abutments.