This study was performed in order to investigate the results of "cyclodialysis ab interno," i.e., a combination of goniotomy and cyclodialysis, in patients suffering from dysgenetic glaucoma. From 1985 to 1993, 69 patients (98 eyes) underwent at least one cyclodialysis ab interno. The development of intraocular pressure was examined 2 days, 4 weeks, 1/2 year, 1 year and 3 years postoperatively after the first and last cyclodialysis ab interno. Additionally, we examined intraoperative bleeding, preoperative pressure level, previous operations, reoperations, age at manifestation, and monocular or binocular manifestation for their influence on the results. The effect the operation had on visual acuity was also examined. One year after the last cyclodialysis ab interno, the IOP was regulated in 77% of the eyes. The prognosis was better for eyes with preoperative pressure values of less than 30 mmHg than for eyes with pressure values of more than 30 mmHg. It was also clearly better when the glaucoma had become manifest at the age of more than one year. Previous operations, intraoperative bleeding, and monocular or binocular manifestation had no influence on the results. In comparison with the data available for goniotomy and trabeculotomy, cyclodialysis ab interno shows a tendency for better results.