Introduction: Study models are an essential part of an orthodontic record. Digital models are now available. Thus the aim of this study is to compare the reliability of measuring the curve of spee on plaster study models and CBCT digital models. Methods: The study consisted of twenty subjects their ages ranged from 17 to 25 years. The subjects were patients seeking orthodontic treatment at the Department of Orthodontics, Faculty of Dentistry, Ain Shams University. All subjects had upper and lower alginate impressions in addition to CBCT taken prior treatment. The curve of spee was measured on both the study models and the CBCT models. Results: The results showed strong agreement in most measurements between the conventional method (plaster model) and the digital method (CBCT model) the correlation coefficients (Pearson's r) for the curve of spee in both methods was (0.992). Correlation was significant at the 0.01 level (2-tailed). Conclusion: Excellent agreement between the measurements for the curve of spee with the plaster study model and digital model was found; CBCT digital models can be an alternative to plaster study models.