OBJECTIVE: The aim of this study was to evaluate whether salivary gland ultrasonography (SGUS) improves the diagnostic performance of the 2012 ACR classification criteria for SS. METHODS: We studied a cohort of 101 patients with suspected SS seen at a single centre in Brittany, France. An SGUS echostructure score ≥2 was considered abnormal. The reference standard was a clinical diagnosis of SS made by a group of experts blinded to SGUS findings. RESULTS: SS was diagnosed in 45 patients. Similar proportions of patients with and without SS had an ocular staining score ≥3. Adding RF positivity and ANA titre ≥1:320 as an alternative to anti-SSA/SSB positivity increased the sensitivity of the serological item without modifying specificity compared with using anti-SSA/SSB alone. SGUS was 60.0% sensitive and 87.5% specific for SS. Adding the SGUS score to the ACR criteria increased sensitivity from 64.4% to 84.4% and only slightly decreased specificity, from 91.1% to 89.3%. CONCLUSION: The diagnostic performance of the ACR classification criteria for SS is notably improved by adding the SGUS score. SGUS should be included in future classification criteria for SS.