In epidemiology and clinical research, the reproducibility of clinical parameters is most important. In this study, we examined the inter-and intra-examiner reliability of each of the following clinical parame -ters: plaque index (PH), gingival index (GI), probing depth (PD), attachment level (AL), and bleeding on probing (BOP). PD, AL, and BOP measurements were carried out with an electronic probe, The Florida Probe®. The measurements were performed on 17 subjects (5 patients and 12 healthy subjects). Clinical parameters were measured twice in each subject at intervals of 1-2 hours. For inter-examiner reliability, the first measurement was performed by one examiner and the second measurement by another examiner. For intra-examiner reliability, each measurement was performed on all subjects by one examiner. Interexaminer reliability of clinical parameters were 0.52 (PH), 0.52 (GI), 0.59 (BOP) (P1I, GI, BOP: Kraemer's Kappa), 0.73 (PD), 0.56 (AL) (PD, AL: correlation coefficient). Intra-examiner reliability of clinical parameters were 0.71 (PH), 0.66 (GI), 0.52 (BOP) (PH, GI, BOP: Kraemer's Kappa), 0.97 (PD), 0.94 (AL) (PD, AL: correlation coefficient). The results indicate that clinical parameters (PH, GI, PD, AL, BOP) can demonstrate good inter-and intra-examiner reliability. J. Jpn. Soc. Periodontol., 41: 144-152, 1999.