Background: Alzheimer's disease dementia (ADD) is an important health problem in the world. Objective: The present study investigated the validity and reliability of a new version of the Frontal Assessment Battery (FAB) named the FAB-phonemic (FAB-P). Methods: A total of 76 patients with ADD, 107 patients with amnestic mild cognitive impairment (aMCI), 37 patients with non-amnestic MCI (naMCI), and 123 healthy controls were included in this study. All participants were evaluated with the FAB-P and the cognitive assessments according to a standard procedure. Results: The global FAB-P scores in patients withADDwere lower than those of patients with aMCI, patients with naMCI, and healthy controls (p < 0.001). Patients with aMCI performed worse than healthy controls (p < 0.001). The interrater reliability, test-retest reliability, and Cronbach's alpha coefficient for the FAB-P were 0.997, 0.819, and 0.736, respectively. The test could distinguish the patients with mild ADD, aMCI, and naMCI from healthy controls with classification accuracy of 89.4%, 70.9%, and 61.6%, respectively. It could also discriminate between the patients with ADD and aMCI, between those with ADD and naMCI, and between those with aMCI and naMCI with classification accuracy of 73.8%, 83.9%, and 58.0%, respectively. The regression analysis revealed that the Montreal Cognitive Assessment and the Stroop Color Word Test Part C had the greatest contribution to FAB-P score variance. Conclusion: The FAB-P is a valid and reliable tool for evaluating frontal lobe function and can effectively discriminate ADD, aMCI, and naMCI.