Purpose: The aim of this study was to evaluate the reliability and agreement of a new computerized planimetric method (CPM) for the measurement and assessment of plaque on all types of removable dental prostheses (RDPs). Materials and Methods: From a database containing 780 images taken following a standardized method for 65 RDPs, 55 images were randomly selected for image analysis. Adobe Photoshop software was used according to standard operating procedure (SOP) by one main examiner two times in different sessions, and one time by three additional examiners. To estimate the intra- and interexaminer reliability, intraclass correlation coefficient ICC(2,1) were used. Three parameters were used to estimate agreement: standard error of measurement (SEM), smallest detectable change at the 95% confidence level (SDC95%), and limits of agreement (LoA) according to the Bland-Altman method. Results: In all steps of the image analysis, both intra- and interexaminer reliability were excellent, with ICC(2,1) values > 0.85 at the 95% confidence level. The intra- and interexaminer values for both the SEMagreement and SDC95% were ≤ 6% and ≤ 17%, respectively. The Bland-Altman analysis revealed a satisfactory level of agreement. Conclusion: This study shows excellent inter- and intraexaminer reproducibility, a satisfactory level of examiner agreement, and acceptable measurement error. Furthermore, the method can be used with all types of RDPs. The CPM is more suitable for clinical research because of its objectivity, reliability, high level of standardization, and ability to detect and quantify small changes in plaque.