Behçet's disease (BD) is a multisystem inflammatory disorder currently classified as a vasculitis. Its etiopathogenesis is unclear, but environmental, genetic and autoimmune factors have been considered. There are ongoing efforts to elucidate the etiology of BD and numerous attempts have been made to identify biomarkers predictive of the course and severity of the disease. Much of this – mostly cross-sectional – work has yielded some valuable results, but more longitudinal studies are needed. This review provides an overview of some of the biomarkers which have been investigated in BD so far, and aims to evaluate their usefulness in the diagnosis and estimation of disease activity. This is exemplified by certain clinical situations. Clinicians, clinical investigators and basic researchers alike are given a concise database of biomarkers studied in association with BD, as well as a reflection of methods for estimation of disease activity.