Although the National Adult Reading Test (NART) is widely used to estimate premorbid intellectual ability in adults with possible or probable dementia, it may be less resilient to the progress of Alzheimer's Disease (AD) than was initially assumed. This paper reports performance at four annual assessments of 78 people with either autopsy confirmed (n = 50) or clinical diagnosis of AD (n = 28). Results indicate that NART score does decline over time and that extent of decline is a function of MMSE score on entry to the study but is not dependent on age, education or time post onset of dementia.