OBJECTIVE : To investigate the role of personality and anxiety to self-report measures of cognition in patients with multiple sclerosis (MS). BACKGROUND : Self-report measures of cognition have consistently been shown to correlate better with depressed mood than neuropsychological test performance in patients with MS, with few studies focusing on the role of anxiety and personality. METHODS : One hundred eight MS patients completed the following: (a) patient and informant report Multiple Sclerosis Neuropsychological Questionnaire (MSNQ); (b) Hospital Anxiety and Depression Scale; (c) cognitive assessment with the Brief Repeatable Battery of Neuropsychological Tests; and (d) personality assessment using the self-report NEO Five-Factor Inventory. RESULTS : Higher patient MSNQ (P-MSNQ) scores (greater reported cognitive dysfunction) were significantly correlated with lower scores on the Paced Auditory Serial Addition Test (PASAT; r=-0.20, P<0.05), increased depression (r=0.45, P<0.01) and anxiety (r=0.54, P<0.01), higher neuroticism (r=0.51, P<0.01), and lower conscientiousness (r=-0.35, P<0.01). After controlling for demographic variables, significant predictors of P-MSNQ scores were anxiety (ΔR=0.272, P<0.001), conscientiousness (ΔR=0.067, P=0.002), and performance on the PASAT (ΔR=0.050, P=0.005). Depression and neuroticism did not contribute significant variance in comparison to anxiety. CONCLUSIONS : Overall, patient self-reports of cognition did not correspond well to neuropsychological performance. Anxiety and conscientiousness contributed significantly to patients' perceptions of their cognitive failings and thus should be taken into account when addressing these complaints.