This study designed to identify the therapeutic efficacy of niclosamide (NCL) in Iraqi patients suffering from active rheumatoid arthritis (RA) who were using etanercept (ETN) for more than 3 months and still had high or moderate active RA. One hundred ten patients suffering from active rheumatoid arthritis (RA) who were using etanercept (ETN) for more than 3 months and still had high or moderate active RA were allocated randomly into two equal groups: one of them treated with 1000 mg/day NCL and the other treated with 1000 mg/day lactose in capsule dosage form. The study duration was 8 weeks. Clinical efficacy of the NCL was measured depending on scoring of the 28-joint Disease Activity Score (DAS28), simple disease activity index (SDAI), clinical disease activity index (CDAI), and Health Assessment Questionnaire Disability Index (HAQ-DI) at the baseline and at the end of the 8-week treatment period. Moreover, blood sample were taken from the patients at baseline and at after 8 weeks of treatment for measurement of the erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), interleukin 1β (IL-1 β), interleukin-6, tumor necrosis factor (TNF-α), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. At the end of the clinical study, patients had good response to NCL when added to the ETN with a high significant improvement in the SJC, TJC, DAS-28, CDAI, SDAI, and HAQ-DI compared to patients who were received placebo drug. In addition to that, 33% of patients achieved an ACR 20% response (ACR20) on NCL and ETN. Of these, 4% achieved ACR50 and another 4% achieved ACR70 response. While those group treated by placebo + ETN, 5% achieved ACR20 response and no one reached to ACR50 or ACR70 response. Twenty-seven percent of RA patients who have taken the NCL achieved moderate EULAR score while only 17% from the group that taken placebo with ETN achieved moderate response. On the other hand, no significant reduction was found in CRP, ESR, TNF-α, and IL-6, while IL-1 β reduced significantly after treatment with NCL. Treatment with NCL also exerts a significant lowering in the serum level of the E-selectin, ICAM1, and VCAM1 when compared to their value in baseline level. In RA disease, the use of NCL as adjuvant with ETN has resulted in a marked reduction in clinical assessment scoring indices and significantly decreased the E-selectin, ICAM-1, and VCAM-1 with marked improvement in the quality of life of patients.