With the increasing popularity of digital models in orthodontics today, the American Board of Orthodontics (ABO) is considering allowing digital models to replace plaster models during the Phase III evaluation process. Digital models offer the convenience of minimal storage requirements, easiertransport, and less potential for damage. Cases could be submitted electronically and graded inadvance, which would significantly lighten theworkload on ABO examiners during the exam.In order for digital models to become an acceptable alternative, they must accurately represent the patients dentition and they must be able to be graded using the ABO Objective Grading System. Many studies have demonstrated excellent accuracy with these models, but until recently, there has been no way to grade them. Currently there are two digital imaging companies that have developed software with ABO grading capability (Geodigm Corporation and Cadent Technologies).The purpose of this study was to evaluate the accuracy and variability of grades obtained by theuse of computer software on digitized 3-dimensionalcasts using the American Board of OrthodonticsObjective Grading System.