This report describes a case of generalized aggressive periodontitis (Stage III, Grade C) requiring periodontal regenerative therapy. The patient was a 35-year-old woman who visited Tokyo Dental College Suidobashi Hospital with the chief complaint of swelling in the maxillary left gingiva. An initial examination revealed 34.5% of sites with a probing depth (PD) of ≥4 mm. The prevalence of sites with bleeding on probing was 29.8%. The plaque control record (PCR) score was 59.8%. Radiographic examination revealed extensive horizontal bone resorption in the maxillary and mandibular molars. Considerable angular bone resorption was observed in teeth #14 and 24. Furcation involvement was observed in teeth #16 and 46. A clinical diagnosis of generalized aggressive periodontitis (Stage III, Grade C) was made, based on which initial periodontal therapy was performed. An improvement was observed in periodontal conditions on re-evaluation. The PCR score was 11.5%. Periodontal surgery was performed for teeth with a residual PD of ≥4 mm. Periodontal regenerative therapy using recombinant human fibroblast growth factor-2 (rhFGF-2) was performed on intrabony defects in #14 and 24. Open flap debridement was performed on #15, 16, 25, and 26. Root separation was performed on #46. Following re-evaluation, an all-ceramic crown was placed on #46, and the patient was placed on supportive periodontal therapy (SPT). During the 1 year of SPT, stable periodontal conditions have been maintained. However, due to the loss of all the secondary molars, the risks of occlusal trauma to the remaining teeth and root surface caries associated with extensive gingival recession following the periodontal treatment remain. Therefore, continued care is necessary to maintain good periodontal conditions.