Chronic kidney disease is commonly diagnosed in cats, but only when it has progressed to more advanced stages. Renal biomarkers are indicators of kidney disease that may be elevated before there is a loss of function. This lecture will cover traditional markers of kidney function (ie urea, creatinine, and SDMA), newer tests that are available (FGF-23, cystatin) and future developments (KIM-1, NGAL). We will discuss the utility of these tests, their limitations, and future directions.