Chronic low back pain (CLBP) in older adults may be disabling and therapeutically challenging, largely because of the inefficacy and/or morbidity associated with traditional pain treatment. We conducted a randomized controlled trial in 200 men and women > or = age 65 with CLBP to evaluate the efficacy of percutaneous electrical nerve stimulation (PENS) with and without general conditioning and aerobic exercise (GCAE), for reducing pain and improving physical function. Participants were randomized to receive (1) PENS, (2) control-PENS (brief electrical stimulation to control for treatment expectancy), (3) PENS+GCAE, or (4) control-PENS+GCAE, twice a week for 6 weeks. All four groups experienced significantly reduced pain (range -2.3 to -4.1 on the McGill Pain Questionnaire short form), improved self-reported disability (range -2.1 to -3.0 on Roland scale) and improved gait velocity (0.04-0.07 m/s), sustained at 6 months. The GCAE groups experienced significantly fewer fear avoidance beliefs immediately post-intervention and at 6 months than non-GCAE groups. There were no significant side effects. Since brief electrical stimulation (i.e., control-PENS) facilitated comparably reduced pain and improved function at 6 months as compared with PENS, the exact dose of electrical stimulation required for analgesia cannot be determined. GCAE was more effective than PENS alone in reducing fear avoidance beliefs, but not in reducing pain or in improving physical function.