Objective: To compare performance on phonological, semantic, and action verbal fluency tasks (VFT) when they are completed in Basque or Spanish in a group of Basque-Spanish bilinguals. Method: 57 healthy bilinguals adult from Basque Country, Spain participated in the study. Inclusion criteria were 18–75 years of age, completed primary school, a score of ≥27 on the Mini-Mental State Examination, a score of ≤4 on Patient Health Questionnaire–9, and be fluent speakers in Basque and Spanish. 61.4% of the sample were women, the mean age was 43.75 ± 16.99, and the mean years of education 15.77 ± 3.27. All participants completed the semantic (animals, fruits, professions), phonological (F, A, S, M, R, P, E, B), and action VFT. The order of languages was counterbalanced. Results: Multivariate analyses of variance revealed significant differences between languages for most tasks (F = 61.30; p < .001). Participants achieved higher scores in the VFT when they were completed in Spanish, with the exception of the action VFT, and letters A and E of the phonological VFT in which they performed similarly in both languages (p's > .05). Conclusion(s): Results suggest that even when Spanish-Basque bilinguals are fluent in both languages, they achieve higher scores in Spanish in most of the VFT. These differences in performance could be explained by disparities in their use of the two languages (e.g. at home, public and private organizations), or by participants' attempts to avoid using Spanish-borrowed words when completing the tasks in Basque. Therefore, different normative data are required for both languages in these tasks.