Periodontal probes are the main instruments that are used to assess the status of the periodontium, either for screening purposes or to evaluate periodontal changes throughout the treatment process. With increased knowledge and understanding of periodontal disease, the probes have evolved from a unidimensional manual shape into a more sophisticated computerised instrument. This is due to the need to increase the accuracy and reproducibility of readings and to improve efficiency (time, effort, money). Each probe has characteristic features that makes it unique and, in some cases, specific and limited to use. The aim of this paper is to present a brief introduction to periodontal disease and the methodology of measuring it, followed by probing limitations. The paper will also discuss the methodology of reducing probing error, examiner calibration and probing reproducibility.