With demographic increases in the aging population, diseases of aging are also increasing, and in particular Alzheimer's disease (AD). Although diagnostic criteria for AD have been developed, early diagnosis of AD is imperfect. The earliest neuropathological changes in AD occur in areas that process olfactory information, and a number of recent studies have demonstrated that olfactory impairments may contribute to detection during the early stages of dementia, especially in AD. Culture is a critical variable that may influence the accuracy of the diagnosis of AD. Although neurocognitive tests are commonly used to detect decline in cognitive functioning, the application of some such tests in the assessment of minority individuals has been questioned. One early study indicated that significant amounts of data, which are used as norms, were collected from Western populations, such as Europeans, North Americans, and Australians. Previous studies have demonstrated the need for norms based on different cultures. Despite significant work in African American and Hispanic American populations, little information is available regarding performance of Japanese Americans on neuropsychological tests. The aim for this study was to examine differences in the performance on neurocognitive tests in Japanese Americans. This study had a total of 100 Japanese Americans (50 individuals who speak English as their first language vs. 50 individuals who speak Japanese as their first language). Their performance was measured with the Boston Naming Test-2 (BNT-2), San Diego Odor Identification Test (SDOIT), Verbal Fluency Test (VFT; FAS and animals), California Verbal Learning Test (CVLT), California Odor Learning Test (COLT), and Brief Visuospatial Memory TestRevised (BVMT-R). Factors which may explain some of the variability between the two groups in the selected neurocognitive tests were investigated: first language (i.e., self report), level of acculturation (as measured by Suinn-Lew Asian Self-Identity Acculturation Scale), years of residence in the United States, quality of education (as measured by the Wide Range Achievement Test-4: Arithmetic and Reading subtest), years of education in English and Japanese, and generation status in the United States. We hypothesized that the background variables such as language, level of acculturation, and years of residence and education in the U.S. would influence test performance on the olfactory- and verbal-based tests. We also predicted that Japanese-dominant speakers would be more likely to perform poorly on olfactory- and verbal-based tests than those who speak English as their primary language. Significant differences between the English-dominant and Japanese-dominant groups in test performance were observed in the current study, with the Japanese-dominant group performing poorer on the measures of naming ability, verbal and olfactory learning/memory and language compared to the English-dominant group. These data from Japanese American cohorts will be a starting point for understanding discrepancies in the neuropsychological test performance between Asian Americans and non-Hispanic Caucasians.