<h3>Background</h3> The identification of patients with rheumatoid arthritis (RA) in the early stages of the disease leads to early treatment and improved outcomes. MSUS is a relatively easy, accessible and low cost method, which has been proven more sensitive in detecting findings suggestive of inflammatory arthritis than clinical or radiographic exams. Evidence shows that MSUS seems to bring additional knowledge when assessing the joints on patients with suspected RA, however, there is still controversy whether it can improve substantial discriminatory value for early arthritis. <h3>Objectives</h3> To assess the diagnostic value of MSUS and optimal cutoff criteria for the diagnosis of RA in patients with arthralgia and non-classified arthritis. <h3>Methods</h3> We conducted a meta-analysis for original studies evaluating ultrasound on patients with arthralgias and non-classified arthritis, published in Pubmed, EMBASE and Cochrane databases until December 2017. Statistical analysis included <i>i)</i> the calculation of sensitivity and specificity for ultrasound <i>ii) summary receiver operating characteristic</i> (SROC) <i>curve</i>s for a linear regression model <i>iii)</i> I squared test for heterogeneity. <h3>Results</h3> Sixteen studies were included in the review. The overall sensitivity and specificity were 0.75 (95% CI 0.62, 0.88) and 0.72 (95% CI 0.60, 0.83) respectively. The overall diagnostic odds ratio (DOR) was 11.45 (95% CI 6.52, 20.11). The relative DOR for studies performed in Asia (10.43, p=0.002), published before 2013 (15.71, p=0.001) and involving MCP (11.27, p=0.003) and MTP (2.78, p=0.021) exhibited higher diagnostic performance. Meta-regression after adjusting for country, year, and type of joint involved, showed that Grey Scale (GS) ≥1 RDOR 6.0 (95% CI 1.6, 22.5; p=0.009) and Power Doppler (PD) ≥1 RDOR 3.9 (95% CI 1.3, 11.7, p=0.018) had greater diagnostic accuracy when compared to higher cutoff values. <h3>Conclusions</h3> MSUS is a valuable diagnostic tool when used in patients with arthralgia and at risk for RA. GS ≥1 and PD ≥1 combined have better discriminative ability for diagnosing RA due that the overall specificity is greater than for either alone. <h3>References</h3> [1] Lage-Hansen PR, et al. Rheumatol Int2017Feb;37(2):179–187. [2] Pratt AG, et al. Arthritis Res Ther2013;15:R118. <h3>Disclosure of Interest</h3> None declared