This study was to determine the differences in simple visual reaction time (SVRT), movement reaction time (MRT) and simulated driving reaction time (SDRT) between younger and older adults while simulating various driving tasks. This study would provide information for future study in determining the limiting factors related to the driving ability. Eighty adults who currently drive, participated in this study and were divided into two age groups (20-35 & 65-80 years old). Each age group had 20 males and 20 females. A computerized simulated driving reaction time system was used to evaluate the participants' SVRT, MRT and SDRT. The SVRT was similar to the traditional reaction time test. The MRT was measured when the participant was in a driving position and quickly moved the right foot from the acceleration pedal to the break pedal as a signal appeared on the computer screen. In the SDRT test, the participant hold a steering wheel and kept the right foot between the break and acceleration pedals, and looked at four white symbols (a left-turn arrow, a right-turn arrow, a forward arrow, and a stop sign) on the computer screen. When the left (right) turn arrow turned green, the participant quickly turned the steering wheel to the left (right). When the forward arrow turned green, the participant quickly pressed the simulated accelerator. When the stop sign turned red, the participant quickly pressed the break pedal. Ten SVRT and 10 MRT trials, and twenty SDRT trials were recorded for each participant. The Mini-Mental State Exam (MMSE) was administrated to obtain information of the cognitive status. Two-Way ANOVA was employed to determine the differences in the selected reaction times and MMSE score. Pearson product-moment correlation analysis was used to determine the relationship between the selected reaction times, and the MMSE score. The younger drivers' SVRT (229.7ms), MRT (440.4ms), and SDRT (565.5ms), were significantly shorter than the older drivers' (269.2, 657.3 & 725.2ms), respectively (p<.01). The younger drivers' MMSE score (33.9) was significantly higher than that (32.3) of the older drivers (p <.01). The MMSE scores were significantly correlated to SVRT (r=-.265, p<.05), MRT (r=-.377, p<.01) and SDRT (r=-.402, p <.01). In summary, the younger drivers have quicker SVRT, MRT and SDRT than the older drivers have and these reaction times are related to the cognitive status. No gender difference was found in the simulated reaction times and the cognitive status for these younger and older adults.Keyword(s): assessment, older adult/aging issues, research