Objective To determine if adding dry needling to a four-week exercise program has an additional benefit compared with adding sham dry needling to the same exercise program in subjects with chronic low back pain. Design Randomized clinical trial. Setting Physiotherapy and Pain Clinic of Alcala University. Subjects Forty-six patients with chronic low back pain. Methods Subjects were randomized to two groups: the dry needling group (N = 23) or sham dry needling group (N = 23). Both groups received a four-week exercise program and before the exercise started a session of dry needling or sham dry needling. Pain (visual analog scale), disability (Roland-Morris Questionnaire), and fear avoidance beliefs (Fear Avoidance Beliefs Questionnaire) were assessed at baseline, after treatment, and at three-month follow-up. Pressure pain thresholds (algometer) were measured at baseline, after the dry needling or the sham dry needling, and after treatment. Results Both groups showed significant improvements for all variables. In the between-group comparison, the dry needling group improved significantly in pain at three-month follow-up and pressure pain thresholds at the end of treatment for all measures, and at three-month follow-up there was no improvement in gluteus medium. Conclusions In chronic low back patients, adding dry needling to a four-week exercise program has an additional benefit in pain and sensitivity compared with adding sham dry needling to the same exercise program. [ABSTRACT FROM AUTHOR]