Suspension seats are widely used in construction machinery to control vibration transmission and reduce discomfort and health risks to drivers. This study was undertaken via laboratory measurements to investigate the dynamic characteristics and performance of a suspension seat of a motor grader prior to optimising ride comfort of the grader. The isolation efficiency of the suspension seat was assessed in accord with ISO 7096: 2000. The vibration transmission of the suspension seat in the vertical direction was examined with different seat configurations and loading conditions. The results showed that the seat suspension was nonlinear, with the transmissibility dependent on the magnitude of excitation and distribution of the vibration energy, and that the transmissibility of the seat measured with a rigid mass differed from that measured with human subjects. The phenomena observed during the experimental study were discussed in some details and conclusions were made.