This report describes the long-term outcomes of nonsurgical periodontal therapy and supportive periodontal treatment (SPT) of a 21-year-old patient affected by generalized aggressive periodontitis at multiple teeth with a compromised prognosis. After 25 years of SPT, no teeth had been extracted and no periodontal pockets associated with bleeding on probing were present. Radiographic analysis showed an improvement in infrabony defects, demonstrating longterm improvement is possible with nonsurgical periodontal treatment provided that smoking is not present and the patient is included in a strict SPT.