It has previously been shown that older adults may be less efficient than younger adults at processing multisensory information, and that older adults with a history of falling may be less efficient than a healthy cohort when processing audio–visual stimuli (Setti et al., 2011). We investigated whether body stance has an effect on older adults’ ability to efficiently process multisensory information and also whether being presented with multisensory stimuli while standing may affect an individual’s balance. This experiment was performed by 44 participants, including both fall-prone older adults and a healthy control cohort. We tested their susceptibility to a sound-induced flash illusion (i.e., Shams et al., 2002), during both sitting and standing positions while measuring balance parameters using body-worn sensors. The results suggest that balance control in fall prone-adults was compromised relative to adults with no falls history, and this was particularly evident whilst they were presented with the auditory-flash illusion but not the non-illusory condition. Also, when the temporal window of the stimulus onset asynchrony was narrow (70 ms) fall-prone adults were more susceptible to the illusion during the standing position compared with their performance while seated, while the performance of older adults with no history of falling was unaffected by a change in position. These results suggest a link between efficient multisensory integration and balance control and have implications for interventions when fall-prone adults encounter complex multisensory information in their environment.