BACKGROUND: Associations between attention-deficit/hyperactivity disorder (ADHD) and chronic pain disorders, such as fibromyalgia, have been reported. However, associations between persistent chronic nonspecific low back pain (CNLBP) and ADHD have not yet been investigated. OBJECTIVES: This study aimed to investigate the positive rates of possible ADHD, as assessed by self-reported ADHD scales, in patients with persistent CNLBP, using data from self-reported questionnaires completed by patients and their families. This study also aimed to compare the self-reported scores obtained from existing standardized data for healthy individuals, and to examine whether the ADHD scale scores of patients with persistent CNLBP are associated with pain variables. STUDY DESIGN: Cross-sectional study. SETTING: The specialized pain clinic at our university hospital. METHODS: This cross-sectional study included 60 consecutive patients with persistent CNLBP who were diagnosed with a possible somatic symptom disorder and were referred to a psychiatrist in our pain clinic. The Conners' Adult ADHD Rating Scales (CAARS) self-report (CAARS-S) and observer-rated (CAARS-O) questionnaires were utilized. We investigated the CAARS scores, and the association between the CAARS subscale scores and pain variables (pain duration and pain Numeric Rating Scale) in patients with persistent CNLBP. RESULTS: Of the 60 patients, 19 (31.7%) were positive on both CAARS-S and CAARS-O questionnaires (T-score > 65). The ADHD indices, which comprised subscales of the CAARS estimating the necessity of treatment for ADHD, were significantly higher in both male and female patients with persistent CNLBP than in the Japanese standardized sample (P < 0.005). CAARS-S hyperactivity/restlessness, CAARS-O hyperactivity/restlessness, and the Diagnostic and Statistical Manual of Mental Disorders, fourth edition hyperactive-impulsive symptom subscale scores also correlated with the pain intensity (P < 0.05). LIMITATIONS: In this study, ADHD tendency was evaluated using only a self-reported questionnaire. Hence in the future, accurate and precise assessments of ADHD symptoms using structured clinical interviews conducted by ADHD experts are warranted. Additionally, the study only included patients with persistent CNLBP. Therefore in the future, it will be valuable to investigate ADHD scale scores (e.g., CAARS) among patients with CNLBP and nonspecific low back pain with larger sample sizes. CONCLUSIONS: Our findings revealed that the subscale scores on an ADHD scale were considerably high in patients with persistent CNLBP. As a previous study of our clinical experience indicates that persistent CNLBP can be substantially relieved by administering ADHD medications, ADHD screening is warranted in the treatment of persistent CNLBP.