This paper examines mathematics teachers' level of acceptance and intention to use the Augmented Reality Geometry Tutorial System (ARGTS), a mobile Augmented Reality (AR) application developed to enhance students' 3D geometric thinking skills. ARGTS was shared with mathematics teachers, who were then surveyed using the Technology Acceptance Model (TAM) to understand their acceptance of the technology. We also examined the external variables of Anxiety, Social Norms and Satisfaction. The effect of the teacher's gender, degree of graduate status and number of years of teaching experience on the subscales of the TAM model were examined. We found that the Perceived Ease of Use (PEU) had a direct effect on the Perceived Usefulness (PU) in accordance with the Technology Acceptance Model (TAM). Both variables together affect Satisfaction (SF), however PEU had no direct effect on Attitude (AT). In addition, while Social Norms (SN) had a direct effect on PU and PEU, there was no direct effect on Behavioural Intention (BI). Anxiety (ANX) had a direct effect on PEU, but no effect on PU and SF. While there was a direct effect of SF on PEU, no direct effect was found on BI. We explain how the results of this study could help improve the understanding of AR acceptance by teachers and provide important guidelines for AR researchers, developers and practitioners.