In rheumatic diseases, biomarkers may serve as surrogate endpoints for diagnosis, prognosis, disease activity, therapeutic response and disease outcome. In recent years a great effort has been made to identify useful tools to establish early diagnosis, prognosis and therapeutic response especially in rheumatoid arthritis (RA). In psoriatic arthritis (PsA) serological biomarkers have been frequently borrowed from RA, but this approach have sometimes lead to inappropriate choices of biomarkers and incorrect conclusions. Furthermore, the heterogeneous spectrum of articular manifestation of PsA and the variable course of the disease can make diagnosis and prognosis difficult. Recently, the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) identified two key areas for biomarkers development in psoriasis and PsA: the diagnosis of the articular disease in patients with psoriasis and the evaluation of joint damage in PsA. In this review we revised the currently available and the new potential markers for PsA, such as serum, genetic, cellular and histological biomarkers, clinical and imaging data, with particular attention on the prognostic aspect in order to identify progressive disease suitable for a more aggressive treatment.