A retrospective study examined the frequency of a feasible or remotely possible indication for regenerative therapy of furcation involvement in a large group of periodontally diseased patients. The judgment about the feasibility of the indication was mainly based on results of current randomized controlled clinical trials with regard to tooth type and location of the furcation lesion. Data from 558 patients treated by two periodontists, one experienced and one in training, were analyzed. Furcation involvement of at least one multirooted tooth was found in 40% and 63% of the two dentists' patients. In only 20% and 27% of their patients was there a potential indication for regenerative furcation treatment. Of 1,134 furcation lesions, 180 (15.9%) were conceivably suitable for this procedure. Only 17 sites with a feasible or remotely possible indication were treated in that way. In most cases, conventional furcational treatment (flap surgery with scaling and root planing) was performed.