The authors investigated the relationship of white-coat hypertension (WCH) with subclinical organ damage and potential relevant mechanisms. A total of 386 untreated patients were enrolled and divided into 204 patients with WCH and 183 with normotension. Flow-mediated dilation (FMD), pulse wave velocity (PWV), intima-media thickness, left ventricular mass index (LVMI), and cystatin C levels were measured. All tests were two-sided, and a P value <.05 was considered statistically significant. The WCH group exhibited higher LVMI and PWV values, decreased E/A ratio and FMD values, and increased prevalence for left ventricular hypertrophy compared with controls (P<.001 for all). Cystatin C was significantly higher in the WCH group compared with controls (P=.035) and was positively associated with LVMI (P<.05 for both). The presence of WCH is associated with more pronounced subclinical organ damage compared with normotension. Cystatin C may play a significant role and therefore warrants further investigation.