Abstract Background The Geriatric Oral Health Assessment Index (GOHAI) was developed and validated in 1990 and translated into Spanish in 1999. Since then, the original version has been used in numerous studies, but it has not been re-evaluated in terms of language in the new generations of older adults. The purpose of this study is to confirm the validity of the Spanish version of the Geriatric Oral Health Assessment Index (GOHAI-SP) after three decades to be used as part of an ongoing field trial. Methods The GOHAI-SP was pilot tested in a focus group to confirm linguistic comprehension. A version with minor language changes was administered to individuals with metabolic syndrome aged 55–75 years from one health care district in southern Spain as part of an ongoing field trial (PREDIMED-Plus). Clinical evaluation included assessment of dental and periodontal status. The psychometric properties of the GOHAI-SP were evaluated through stability and internal consistency measures, and concurrent and discriminant validity were assessed. Results The new version of the GOHAI-SP was administered to 100 individuals. The application time was reduced by 7 min. The alpha value for reliability was 0.87. The item-scale correlation coefficients ranged from 0.54 to 0.75, and the test–re-test correlation for the total score was 0.75. There were inverse correlations between GOHAI-SP scores and the number of lost teeth and the decayed-missing-filled teeth index (p < 0.001). Conclusions The GOHAI-SP questionnaire remains a valid and useful tool to assess oral health-related quality of life in primary health care settings. A linguistic update of the questionnaire brought improvements to the instrument application. Trial registration The PREDIMED-Plus trial is registered in the ISRCTN registry with reference number ISRCTN89898870. Registration date: 4th July 2014.