Patients with amyotrophic lateral sclerosis (ALS) often show deficits on neuropsychological tests that tap functions related to the integrity of the prefrontal lobes. Various aspects of personality are also known to be mediated by prefrontal regions, particularly ventromedial prefrontal cortex (vmPFC). Other than apathy, personality changes have not been widely reported in patients with ALS, although clinical observations indicate such changes might be relatively common. Here, we report on a middle-aged woman with bulbar onset ALS (diagnosed 06/2011, examined in Spring, 2012) whose neuropsychological exam did not reveal cognitive deficits. She performed normally on tests of executive functioning. Self-report measures of mood and personality were unremarkable. However, significant personality changes subsequent to disease onset were reported by her husband and two daughters, and these changes were quantified with the Iowa Scales of Personality Change. Results show that personality disturbance may manifest in the absence of notable cognitive changes in ALS, and careful assessment of personality may be important for documenting early neurobehavioral changes in some ALS patients. Findings also show that patients with ALS may not have good insight into personality changes, underscoring the importance of acquiring collateral information. More generally, the results provide further evidence that ALS may compromise the integrity of ventromedial prefrontal regions.