Aerosol deposition efficiency in airway is useful for particle matter exposure assessment and inhaled drug delivery industry. Upper airway cast is a conventional method for airway deposition studies. The object of this study is to characterize the artificial cast deposition efficiency by comparing with in vivo measurements of the same subject. This study recruited a Taiwanese healthy male adult volunteer to take computed tomography (CT) scan, and the dimensions of the cast were referred to the CT scan images. For aerosol deposition test, a TSI constant output and an ultrasonic atomizing nozzle were used to generate submicro-meter-sized and micrometer-sized aerosols, respectively. The aerosol output was then neutralized by a radioactive source, 25 mCi Am241, to the Boltzmann charge equilibrium. A Scanning Mobility Particle Sizer (for particle < 0.7 μm) and an Aerosol Particle Sizer (for particles > 0.7 μm) were used to measure the aerosol concentration and size distribution upstream and downstream of the casts. A Fast Mobility Paticle Sizer was used to measure the aerosol deposition in the nasal cavity while the subjects held breaths. The breath holding maneuvers of the subject would affect aerosol depositions significantly. The nasal-in-mouth-out aerosol deposition through the cast correlated reasonably well with that through the same human subject. However, the CT scan image takes a well trained ENT doctor to correctly interpret. Otherwise, some of the sinus cavity might be treated as the air pathways. For micrometer-sized aerosols, the deposition efficiency in the casts increased with increasing sampling flow, indicating that inertial impaction was the dominating mechanism.