Objectives: We sought to determine whether cranberry juice consumption would ameliorate laboratory and clinical measurements of disease activity in people with rheumatoid arthritis receiving fish oil supplementation.Methods: A prospective study was performed with 62 people with rheumatoid arthritis. We analyzed C-reactive protein modification of the Disease Activity Score-28 (DAS28-CRP) and inflammatory markers. The first group was assigned to eat their typical diet, a second group was asked to consume 3 g of fish oil -3 fatty acids daily, and a third group received both 3 g of fish oil n-3 fatty acids and 500 mL of reduced-calorie cranberry juice daily.Results: Compared with baseline values, the group receiving both fish oil and cranberry juice showed reductions in erythrocyte sedimentation rate (P = 0.033), C-reactive protein (P = 0.002), DAS28-CRP (P = 0.001), adiponectin (P = 0.021), and interleukin-6 levels (P = 0.045), whereas the fish oil group showed decreased DAS28-CRP (P = 0.0261) and adiponectin (P = 0.0239). Differences across treatments showed that the group receiving both fish oil and cranberry experienced reductions (P < 0.05) in erythrocyte sedimentation rate and C-reactive protein compared to the control group and the group treated with fish oil alone, and a reduction in DAS28-CRP was verified when the fish oil and cranberry group was compared to the control group.Conclusions: The ingestion of cranberry juice adds beneficial effects to fish oil supplementation, decreasing disease activity and inflammatory biomarkers in people with rheumatoid arthritis.