Many functional imaging studies have demonstrated age-related alterations in cerebral blood flow during the resting state. However, few studies have addressed possible differences in functional response to cerebral activation. We assessed the response of visual cortex to photic stimulation in 9 normal elderly subjects and 17 normal younger subjects with blood oxygenation level dependent functional magnetic resonance imaging. We found that the amplitude of response in elderly subjects was significantly decreased compared to younger subjects (2.5 +/- 1.0% versus 4.0 +/- 1.6%, p = 0.01), suggesting a reduction in functional activation or an age-related alteration in the coupling of blood oxygenation to focal activation.