This open study was undertaken to investigate the outcome of autotransplanted teeth over a 6-year period. The subjects were 296 patients who underwent autotransplantation in the 6-year period September 1986-August 1992 and outcome was measured by considering root formation, occlusion, endodontal and periodontal complications. 18 patients were excluded because of inadequate notes or radiographs (n = 3) or because they were lost to follow-up (n = 15). The groups were divided into open apex and closed apex, and duration of follow up was 6 months-5 years. Aplasia was the indication for operation in 158 (77 percent) of the open apex group but only 10 (14 percent) of the closed apex group, whereas caries and associated disease was the most common in the latter (n = 45, 61 percent compared with 20, 10 percent). There were 24 complete failures, 12 in each group (p <0.01). Only 7 teeth in total developed full roots, and 159 showed incomplete growth. In the open apex group 112 teeth were in occlusal contact and 4 were extracted for severe infraocclusion. In the closed apex group there were 10 cases of mild infraocclusion, none of which required treatment. There were 7 cases of pulp necrosis in the open apex group, 4 of which required extraction. Two teeth in the closed apex group were extracted for endodontic reasons. Only 1 tooth (in the closed apex group) had to be extracted for periodontal reasons. Autotransplantation is a reliable method with a good prognosis for donor teeth with both open and closed apexes. The technique is applicable whatever the aetiology of the agenesis, and is worthy of consideration should there be a suitable donor tooth.