Obese aging population is increasing in the United States, and obese elderly experience fall twice as frequent as their lean counterparts. However, the mechanisms of older obese adults fall are still not clear. It is not known whether the obese elderly has more functional mobility impairments than their lean counterparts, and consequently have increased risks of falls. It was hypothesized that obese elderly have more functional mobility impairments compared with their healthy weight counterparts. Six lean and six obese community-dwelling elderly participated in the study. "Timed up & go" test was used to quantify the functional mobility for both lean and obese elderly. Stopwatch and custom-made inertial measurement units were used to obtain the temporal and kinematic parameters. The results showed that there is no significant difference in overall time to complete the "timed up & go" task, but significant difference in anterior posterior acceleration, time to reach the peak extension angular velocity from initiation and double support time between lean and obese groups of participants. Therefore, we concluded that older obese adults have some functional mobility impairments compared with their lean counterparts but the completion time of the "timed up & go" test may not be able to differentiate these individuals. Our results also suggested that obese elderly might have more muscular impairments than their healthy weight counterparts, which can result in higher fall risks. Future studies are warranted to investigate the mechanisms of increased fall risks among obese elderly.