Background: The aim of this study was to validate a Spanish version of the Chronic Pain Acceptance Questionnaire (CPAQ). Pain acceptance is the process of giving up the struggle with pain and learning to live a worthwhile life despite it. The Chronic Pain Acceptance Questionnaire (CPAQ) is the questionnaire most often used to measure pain acceptance in chronic pain populations.Methods: A total of 205 Spanish patients diagnosed with fibromyalgia syndrome who attended our pain clinic were asked to complete a battery of psychometric instruments: the Pain Visual Analogue Scale (PVAS) for pain intensity, the Hospital Anxiety and Depression Scale (HADS), the Medical Outcome Study Short Form 36 (SF-36), the Pain Catastrophising Scale (PCS) and the Fibromyalgia Impact Questionnaire (FIQ).Results: Analysis of results showed that the Spanish CPAQ had good test-retest reliability (intraclass correlation coefficient 0.83) and internal consistency reliability (Cronbach's α: 0.83). The Spanish CPAQ score significantly correlated with pain intensity, anxiety, depression, pain catastrophising, health status and physical and psychosocial disability. The Scree plot and a Principal Components Factor analysis confirmed the same two-factor construct as the original English CPAQ.Conclusion: The Spanish CPAQ is a reliable clinical assessment tool with valid construct validity for the acceptance measurement among a sample of Spanish fibromyalgia patients. This study will make it easier to assess pain acceptance in Spanish populations with fibromyalgia.