Drivers and passengers are exposed to multi-axis vibration in real driving conditions. Excessive pitch motion experienced when vehicle travelling on some road conditions could worsen ride comfort. A 15 Degree-of-Freedom (DOF) mathematical model of vehicle-human system for predicting ride comfort was developed based on a sport utility vehicle. While the vehicle model was calibrated with 4-poster rig tests, the parameters of the seat-human model were determined through a seat vibration test with 8 male subjects. The model was then used to predict the ride vibration of seated human body when the vehicle was subject primarily to combined vertical and pitch motions. Comparison between the model prediction and a field test on a sine wave road showed reasonably good agreement. The model can be further developed to improve its fidelity and application by, for example, taking into account the fore-and-aft motion of the seat and occupant.