Chronic kidney disease affects approximately 19 million adult Americans, and its incidence is increasing rapidly. Diabetes and hypertension are the underlying causes in most cases of chronic kidney disease. Evidence suggests that progression to kidney failure can be delayed or prevented by controlling blood sugar levels and blood pressure and by treating proteinuria. Unfortunately, chronic kidney disease often is overlooked in its earliest, most treatable stages. Guidelines from the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) recommend estimating glomerular filtration rate and screening for albuminuria in patients with risk factors for chronic kidney disease, including diabetes, hypertension, systemic illnesses, age greater than 60 years, and family history of chronic kidney disease. The glomerular filtration rate, calculated by using a prediction equation, detects chronic kidney disease more accurately than does the serum creatinine level alone; the glomerular filtration rate also is used for disease staging. In most clinical situations, analysis of random urine samples to determine the albumin-creatinine or protein-creatinine ratio has replaced analysis of timed urine collections. When chronic kidney disease is detected, an attempt should be made to identify and treat the specific underlying condition(s). The KDOQI guidelines define major treatment goals for all patients with chronic kidney disease. These goals include slowing disease progression, detecting and treating complications, and managing cardiovascular risk factors. Primary care physicians have an important role in detecting chronic kidney disease early, in instituting measures to slow disease progression, and in providing timely referral to a nephrologist.