Four clinical methods to evaluate healing after reconstructive therapy of intraosseous periodontal defects were compared: 1. probing attachment level, 2. probing bone level, 3. entry/re-entry bone height measurements, 4. radiographic bone height determinations. Thirteen patients with a total of 33 defects volunteered for the study. It was found that the depth of the lesions recorded by the various methods showed differences which seem to relate to the varying nature of the methods. On the average, the periodontal probe penetrated 0.8 mm deeper during probing for bone level than during probing for attachment level and another 0.3 mm deeper after denudation of the lesions during entry/re-entry. The average gain of periodontal support following treatment was approximately 1.4 mm as recorded by probing attachment level, probing bone level and entry/re-entry bone height determinations, respectively. A high degree of correlation was found between all three probing methods when the changes following therapy for the individual sites were compared (r = 0.85, 0.75 and 0.81, respectively). Radiographic bone height showed lower degrees of correlation with all three probing parameters (r = 0.45, 0.46 and 0.47, respectively).