MicroRNAs (miRNAs) are small endogenous regulatory RNA molecules, which have emerged as potential therapeutic targets and biomarkers in autoimmunity. Here, we investigated serum miRNA levels in Psoriatic arthritis (PsA) patients and further assessed a serum miRNA signature in therapeutic responder versus non-responder PsA patients.Serum samples were collected from healthy controls (n=20) and PsA (n=31) and clinical demographics obtained. To examine circulatory miRNA in serum from HC and PsA patients a focussed immunology miRNA panel was analysed utilising a miRNA Fireplex assay. MiRNA expression was further assessed in responders versus non responders according to the EULAR response criteria RESULTS: Six miRNA (miR-221-3p, miR-130a-3p, miR-146a-5p, miR-151-5p, miR-26a-5p and miR-21-5p) were significantly higher in PsA compared to healthy controls (all p<0.05), with high specificity and sensitivity determined by receiver operating characteristic (ROC) curve analysis. Analysis of responder vs non-responders demonstrated higher baseline levels of miR- 221-3p, miR-130a-3p, miR-146a-5p, miR-151-5p and miR-26a-5p were associated with therapeutic response.This study identified a six-serum microRNA signature that could be attractive candidates as non-invasive markers for PsA, and may help to elucidate the disease pathogenesis.