Rheumatoid arthritis is a chronic inflammatory autoimmune disease of unknown etiology, many cytokines play an important role in the pathogenesis of RA, and they include TNF-α, IL-1, IL-6 and IL-17 which is a novel pro-inflammatory cytokine that plays an important role in initiation and progression of cartilage and bone destruction. Objective: The aim of the present study was to measure serum and synovial levels of IL-17 in patients with RA; assessment of disease activity and severity using modified Ritchie articular index, DAS-28 scoring system and Functional status assessment; and correlation of serum and synovial levels of IL-17 with RA disease activity parameters. Methods: The present study comprised two groups: Group I consists of thirty adult active RA patients with knee effusion and receiving DMARDs therapy (22 females and 8 males), with age ranged from 22 to 64 years with a mean of 41.47±11.49 years and disease duration ranging from 3 to 20 years with a mean of 9.5±4.16 years. Group II consists of thirteen healthy adults (10 females and 3 males) with age ranging from 20 to 60 years with a mean of 39.08 ± 14.19 years, served as a control group.Results: RA patients showed a statistically significant higher mean serum IL-17 level than healthy controls (11.25 ± 9.67 versus 0.6 ± 1.4 pg/ml, respectively, p=0). In addition, synovial IL-17 levels showed a statistically significant positive correlation with serum IL-17 levels (r=0.5 and p=0.005). No significant correlations were found between both serum and synovial IL-17 levels and patients’ ages, age at disease onset and disease duration. RA patients with negative RF had non-significantly higher mean serum IL-17 levels (12 ± 9.86 pg/ml) compared to those with positive RF (10.82 ± 9.81 pg/ml and p = 0.839), however, the mean synovial IL-17 levels were nearly the same. Statistically significant positive correlations were found between both serum and synovial IL-17 levels and DAS-28 scores (r = 0.556, 0.392 and p = 0.001, 0.032, respectively). RA patients with classes III and IV functional status showed statistically significantly higher mean serum IL-17 levels (17.53 ± 13.43 pg/ml) than classes I and II (8.97 ± 6.97 pg/ml and p = 0.009). Conclusion: We can conclude that serum and synovial IL-17 levels are elevated in patients with RA which parallels the degree of disease activity and can be used as a specific marker for more aggressive joint involvement and damage