A study was done to evaluate long-term results of treating 387 maxillary molars with furcation involvement in 100 patients with chronic destructive periodontal disease. Results showed a favorable long term functional survival rate of 341 teeth (88%) 5 to 24 years after treatment, despite the fact that many teeth had at least one root with 50% or less of bone support before treatment. Of the 46 teeth (12%) that were ultimately extracted, 25 were present for a significant length of time (6 to 18 years) before extraction. The radiographs of 292 teeth (75%) showed no significant change in bone support 5 to 24 years after treatement, while those of 8 teeth (2%) suggested improvement. There was perceptible increase in bone loss in 41 teeth (11%). Forty-six (12 %) were extracted. All periodontally involved teeth in each patient of the study were treated. Specific treatment for maxillary molars with furaction involvement included soft tissue therapy; coronal reshaping, if indicated; and instruction in home care. Considerable emphasis was placed on improving occlusal function. In no case was root amputation, hemisection, osseous surgery, or reshaping of the cervical area of the tooth done. A total of 366 (94%) of the teeth did not have endodontic therapy before, during, or after the study. Therefore endodontic therapy was not a significant factor in retention of the 341 teeth.