A novel telecentric offset reflective imaging system (TORIS) is presented for terahertz medical diagnostic imaging and spectroscopy applications. The imaging system design employs dual-mirror scanning to address slow mechanical scanning, limited field-of-view and variable incidence angle limitations that typically impact in vivo terahertz imaging. The system achieves uniform resolution across a 50x50 mm2 field of view across WR-2.2 (325–500 GHz) and WR-1.5 (500–700 GHz) rectangular waveguide frequency bands. Consistent beam focus was demonstrated with a maximum deviation of 2.7° from normal incidence and beam waist of 2.1 λ at the edge of the field of view.