Osteoarthritis (OA) is a disease of the whole joint, including synovium, bone and cartilage. OA is a slow degenerative and very heterogeneous disease, with both varying levels of disease activity and progression. Biomarkers are urgently needed to assist drug developers in selecting and developing the projects with the highest chance of success. Biomarkers for enrichment of clinical studies, early efficacy as well as other diagnostic tools are needed. Osteoporosis and OA have many similarities. In osteoporosis an armamentarium of treatments are now available with high clinical efficacy and well-described effects on biomarkers. Possibly, lessons learned from the osteoporosis field in the use of biomarkers may be applied in the OA field, from both technical and scientific perspectives. To help guide the way, the FDA has recently published the BEST guidelines, to facilitate obtaining a common vocabulary to assist biomarker researchers. In the current review, we will review the biomarkers of OA, with emphasis on bone, cartilage and synovial biomarkers, and draw clear perspectives to the use of biomarkers for drug development and clinical practice in the osteoporosis field.