The main scope of this research is to study the effects of vibration on the seated human body in vertical direction. In this study, a series/parallel 4-degree-of-freedom lumped parameter model consisting of head/neck, upper torso, viscera, and lower torso is employed for this purpose. Transmissibility analysis was performed to study the biomechanical behaviour of the internal organs in response to the shock loads. Simulation study clearly illustrates the degree of intensity of the vibrational effects transmitted from various internal organs to head/neck system. Furthermore, the problem under investigation reveals the irreparable effects of the force transmitted by internal organs during accidents.