The Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines recommend that serum parathyroid hormone (PTH) concentration of patients with chronic kidney disease (CKD) should be measured regularly and maintained within target ranges that are defined according to the stage of CKD (e.g., 150-300 pg/ml in patients with CKD stage 5). The quality of the PTH assay is of paramount importance, as it contributes to the therapeutic decision. Indeed, when the PTH concentration is above these target values, drugs that decrease PTH secretion, such as active vitamin D compounds or calcimimetic agents, may be given and the doses are then adapted according to the evolution of the PTH concentration. By contrast, if the PTH concentration is below the target range, any treatment that may decrease PTH secretion is stopped to avoid adynamic bone disease and associated extra-skeletal calcifications. The aim of this article is to discuss the main features and pitfalls related to PTH measurement in the setting of CKD.