Biomarker research aims to provide better diagnostic and prognostic tools, potentially leading to improved treatments for the condition. Biomarker research in osteoarthritis is a field of study focused on identifying and understanding specific molecules, genes, or other measurable indicators that can help diagnose, predict, and monitor the progression of osteoarthritis. These biomarkers can be found in blood, synovial fluid or urine. Osteoarthritis is a degenerative joint condition that causes pain, stiffness, and limited movement due to the breakdown of cartilage in the joints. There are a significant number of studies investigating possible biomarkers which may be useful in the diagnosis and prognosis of osteoarthritis. These biomarkers are included in the groups of synthesis and degradation of bone/cargilage/synovium, inflammation, metabolic parameters and microRNAs. In this book chapter, we aim to focus the current status of studies about cartilage oligomeric matrix protein, which is an indicator of cartilage degradation. When we evaluate the current literature findings, we can say that cartilage oligomeric matrix protein may be a promosing biomarker for the diagnosis of osteoarthritis, but there is not sufficient data for the role of cartilage oligomeric matrix protein in the prognosis of osteoarthritis.