Although primary Sjögren's syndrome (pSS) is a mild indolent chronic disease mainly characterized by mucosal dryness in the majority of cases, a consistent subgroup of patients display extra-glandular manifestations. Virtually any organs and systems can be affected, leading to a more serious disease prognosis. Therefore, the prompt identification of patients at higher risk of extra-glandular manifestations is necessary to start a thorough follow up and an aggressive treatment. The aim of this review article is to provide an overview of epidemiological, clinical and serological features of extra-glandular manifestations in pSS as well as current knowledge about putative biomarkers useful in clinical practice.