This study compared the intra- and inter-examiner reliability of the Florida Probe, Florida Disk Probe, and conventional periodontal probe. Using these instruments, each of three examiners made repeated measurements of probing depth (using the Florida Probe and conventional probe), relative attachment level (using the Florida Disk Probe), and clinical attachment level (using a conventional probe) at posterior, proximal sites in 10 subjects with early periodontitis. The mean intra-examiner standard deviation of differences in repeated probing depth measurements ranged from 0.46 to 0.77 mm demonstrating similar levels of reproducibility between the Florida Probe and conventional probe. The mean intra-examiner standard deviation of differences in repeated relative attachment level measurements using the Florida Disk Probe ranged from 0.44 to 0.57 mm using double passes and from 0.98 to 1.41 mm using single passes of measurements. For clinical attachment level measurements obtained using single passes of measurements with a conventional probe, the mean intra-examiner standard deviation of differences ranged from 0.78 to 0.95 mm. Inter-examiner variability was generally greater than intra-examiner variability for all instruments. It was concluded that double passes with the Florida Disk Probe offers significant advantages for measuring relative attachment level in longitudinal studies of early periodontitis when decisions for change must be made as soon as possible.