Osteoarthritis is a chronic disease for which no efficacious medical intervention is yet available. Recent disappointments in late-stage clinical development of disease-modifying osteoarthritic drugs (DMOADs) have precipitated efforts in biomarker discovery aimed at developing an analytical tool box with the potential to improve the clinical development process. In this review, we seek to provide an overview of the biochemical marker repertoire currently available with a special focus on data originating from their application in clinical development programmes. Finally, we discuss possible directions in future biomarker research.