In this study we examine the locus of a prospective memory deficit in an individual with multiple sclerosis. Extensive psychometric and neuropsychological testing revealed above average to superior general intelligence, retrospective and autobiographical memory, short-term/working memory and executive functions. In contrast, the individual demonstrated poor prospective memory on a variety of measures incorporating naturalistic, self-report, and laboratory methods. This deficit appeared to arise from a disruption of processes underlying strategic monitoring. These data clearly demonstrate that impaired prospective memory can exist in the presence of an otherwise intact neuropsychological profile.