OBJECTIVE: The aim of this multicenter study was to evaluate the efficacy, safety, and tolerability of noninvasive cortical electrostimulation in the management of fibromyalgia (FM). DESIGN: A prospective, randomized, double-blind, placebo-controlled design was used. Setting.  Subjects received therapy at two different outpatient clinical locations. PATIENTS: There were 77 subjects meeting the American College of Rheumatology 1990 classification criteria for FM. Intervention.  Thirty-nine (39) active treatment (AT) FM patients and 38 placebo controls received 22 applications of either noninvasive cortical electrostimulation or a sham therapy over an 11-week period. OUTCOME MEASURES: The primary outcome measures were the number of tender points (TePs) and pressure pain threshold (PPT). Secondary outcome measures were responses to the Fibromyalgia Impact Questionnaire (FIQ), Symptom Checklist-90 (SCL-90), Beck Depression Inventory-II, and a novel sleep questionnaire, all evaluated at baseline and at the end of treatment. RESULTS: Intervention provided significant improvements in TeP measures: compared with placebo, the AT patients improved in the number of positive TePs (-7.4 vs -0.2, P<0.001) and the PPT (19.6 vs -3.2, P<0.001). Most secondary outcomes also improved more in the AT group: total FIQ score (-15.5 vs -5.6, P=0.03), FIQ pain (-2.0 vs -0.6, P=0.03), FIQ fatigue (-2.0 vs -0.4, P=0.02), and FIQ refreshing sleep (-2.1 vs -0.7, P=0.02); and while FIQ function improved (-1.0 vs -0.2), the between-group change had a 14% likelihood of occurring due to chance (P=0.14). There were no significant side effects observed. CONCLUSIONS: Noninvasive cortical electrostimulation in FM patients provided modest improvements in pain, TeP measures, fatigue, and sleep; and the treatment was well tolerated. This form of therapy could potentially provide worthwhile adjunctive symptom relief for FM patients.