Informant ratings of cognitive dysfunction have been demonstrated to be more accurate than self ratings in many neurological populations. The current study investigated the accuracy of self and informant ratings of executive dysfunction, the factors contributing to discrepancies between self and informant ratings, and the factors contributing to the ratings themselves in a multiple sclerosis (MS) and control sample. 97 individuals with MS and 27 healthy controls completed a neuropsychological battery, self-ratings of depression, and the Dysexecutive Questionnaire (DEX), a measure of executive dysfunction. DEX informant ratings and informant ratings of depression were obtained for all participants. Self DEX ratings were significantly different between the MS and control groups with the MS participants rating themselves as significantly more impaired. However, informant ratings were similar between the two groups. For the MS participants, objective performance on executive tasks was more highly correlated with self DEX ratings than with informant DEX ratings. Groups were created to examine factors related to discrepancies between self DEX ratings and objective performance on executive tasks, informant DEX ratings and objective performance on executive tasks, and between self DEX and informant DEX ratings. Results indicated that discrepancies between self DEX ratings and objective performance on executive tasks were not related to executive functioning or depression for either the MS or the control groups. However, the discrepancies between informant DEX ratings and objective performance on executive tasks were related to executive functioning for the MS participants. The participants whose informants underestimated their problems with executive functioning performed the worst, suggesting that informants may be overlooking the cognitive impairments of significantly impaired MS patients. Though the discrepancy between self and informant ratings of cognitive impairment has been used as a measure of insight in clinical and research applications, it was not significantly correlated with cognitive performance for either group. MS participants with higher levels of depression had higher self than informant DEX ratings. Implications of these findings are discussed regarding reliability of self-report in MS populations, the influence of depression in ratings, and the relationship between executive functioning and anosognosia.