Aim: To evaluate the accuracy of Invisalign technology in achieving predicted tooth positions with respect to six degrees of freedom. Materials and Methods: The post-treatment models of 30 patients treated with Invisalign were digitally superimposed on corresponding ClinCheck models using best-fit surface-based registration. Differences between the two models for each tooth were measured in six dimensions: the mesial-distal, buccal-lingual, and occlusal-gingival directions, as well as for tip, torque, and rotation. Differences were tested for statistical significance with P < 0.05 considered statistically significant. Differences larger than 0.5 mm for linear measurements and 2 degrees for angular measurements were considered clinically relevant. Results: Maxillary second molars had statistically significantly more buccal crown torque than predicted in the ClinCheck models. This was the only difference that was also clinically relevant. Anterior teeth were positioned more occlusally than predicted, rotation of rounded teeth was incomplete, and movement of posterior teeth in all dimensions was not fully achieved; although these differences were statistically significant, they were not large enough to be clinically relevant. Conclusions: In general, Invisalign aligners are able to achieve predicted tooth positions with high accuracy.