Although cognitive deficits are common in persons with multiple sclerosis (MS), the relationship between subjective complaints and objective impairment is sometimes obscured. To elaborate this issue, the present study examined the relationship between subjective complaints of dysexecutive syndrome, neuropsychological performance, and self-reported activities of daily living in 42 people with MS and 13 control participants. Regression analyses revealed that subjective complaints of impairment, measured by the Frontal Systems Behavior Scale (FrSBe), emerged as a significant predictor of neuropsychological deficit and poor adaptive function. Accordingly, subjective complaints of dysexecutive function in MS may serve as a potent indicator of cognitive and functional impairment. Implications for research and clinical practice are discussed.