This study was aimed to validate the American Speech-Language-Hearing Association Functional Assessment of Communication Skills (ASHA FACS) for a Brazilian population. The scale was translated and adapted into Portuguese. Thirty-two patients with mild Alzheimer disease (AD), 25 patients with moderate AD, and 51 elderly without dementia were examined with Mini Mental State Examination, Geriatric Depression Scale, and Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog). The ASHA FACS was answered by their relative/caregiver. The scale's internal consistency, its inter-examiner and intra-examiner's reproducibility, and scale's criterion validity were researched by correlation with ADAS-cog. The sensitivity and specificity were also researched. Statistical analyses indicated that the ASHA FACS has excellent internal consistency (Cronbach α=0.955), test-retest reliability (interclass correlation coefficient=0.995; P<0.001), and inter-examiners (interclass correlation coefficient=0.998; P<0.001). It showed excellent criterion validity when correlated with ADAS-cog. The ASHA FACS scale showed good sensitivity (75.0%) and specificity (82.4%) values once it is an ecologic and broad evaluation. The ASHA FACS Portuguese version is a valid and reliable instrument to verify communication alterations in AD patients and fills an important gap of efficiency indicators for speech language therapy in our country.