Treatment of intrabony periodontal defects with an enamel matrix derivative (EMD) has been demonstrated, in the short term, to result in periodontal regeneration and to significantly improve clinical parameters such as probing depth (PD) and clinical attachment level (CAL). The present study evaluated deep intrabony defect sites at 9 years after treatment with EMD. Twenty-one patients with a total of 26 deep intrabony defects with PD >= 6 mm and intrabony depth >= 3 mm, as identified by probing and radiographs, were consecutively treated with EMD. PD, recession of the gingival margin (GR), and CAL were evaluated prior to treatment and at 1 and 9 years after treatment. At 1 year, mean PD was significantly reduced. At 9 years, mean PD was statistically significantly increased versus the 1-year results but still significantly improved versus baseline. After 1 year, mean GR had increased significantly; at 9 years, measurements showed statistically significant improvements compared to the 1-year results and baseline. The mean CAL changed from 10.0 ± 2.3 mm at baseline to 6.8 ± 2.3 mm at 1 year and to 7.0 ± 1.9 mm at 9 years. No treated teeth were lost during the observation period. The clinical improvements obtained following treatment with EMD can be maintained over a period of 9 years.