The purpose of this research was to analyze the calculation abilities in Alzheimer Disease (AD). Twenty right-handed patients meeting the DSM-IV (American Psychiatric Association, 1994) criteria for AD were studied. Age ranged from 64- to 88-year-old. A neuropsychological test battery including language, memory, constructional abilities, attention, mathematics, and abstraction tests was administered. In addition, the Mini-Mental State Exam (MMSE) (Folstein, Folstein, McHugh, 1975) was also administered. Mathematical subtests correlated higher than the MMSE with the scores in the different neuropsychological tests. Highest correlations of the mathematical subtests were observed with language repetition, non-verbal memory, and attention tasks. It is proposed that mathematical ability tests represent in AD an excellent predictor of general intellectual performance. It is further proposed that disturbances in arithmetical ability should be included as a diagnostic criteria for AD.