Introduction: The specific diagnosis of toxic encephalopathy (TE) by chronic exposure to neurotoxics presents difficulties, mainly due to lack of consensus of clinical diagnostic criteria. The EUROQUEST (EQ) is a multicultural tool proposed for using in epidemiological studies on neurotoxicity. The aim of this study was to validate the Spanish version of this questionnaire for using as a diagnostic and prevention tool in the workplace. Methods: After translation and cultural adaptation, leading to a final questionnaire in Spanish, validation was performed by asking a total of 759 people to complete the questionnaire, of whom 292 were workers exposed to neurotoxic solvents, 391 non-exposed workers, and 22 patients diagnosed with chronic alcoholism. Results: In the analysis of the reliability, the Cronbach a value for the questionnaire was 0.94, indicating very high internal consistency. The test-retest reproducibility analysis was highly significant (r=0.91, P<.001). In the analysis of the validity, comparing the three study groups, the mean scores of the questions included in each of the dimensions of the test (ANOVA) detected major differences in the dimensions that assess cognitive symptoms, depressive disorders, sleep and psychopathological symptoms. After factor analysis obtained a total of nine axes, allowing a clear distinction between the three study groups. (C) 2013 Sociedad Espanola de Neurologia. Published by Elsevier Espana, S.L.U. All rights reserved.