IntroductionAdaptation and validation to the Basque language of tests to assess advanced cognitive impairment is a not covered need for Basque-speaking people. The present work shows the validation of the Basque version of the Severe Mini Mental State Examination (SMMSE). Material and methodsA total of 109 people with advanced dementia (MEC<15) took part in the validation study, and were classified as GDS 5-7 on the Geriatric Depression Scale (GDS). All participants were Spanish-Basque bilingual. ResultsIt was shown that SMMSE-eus has a high internal consistency (alpha=0.92), a good test-retest reliability (r=0.88; P<.01), and a high inter-rater reliability (CCI=0.99; P<.00) for the overall score, as well as for each item. ConclusionsBoth the high internal consistency and inter-rater reliability, and to a lesser extent, test-retest reliability, made the SMMSE-eus a valid test for the brief assessment of cognitive status in people with advanced dementia in Basque-speaking people. For this reason, the SMMSE-eus is a usable and reliable alternative for assessing Basque-speaking people in their mother-tongue, or preferred language.