Abstract: Objective To investigate the incidence of white coat effect（WCE） and to analyze the relationship between WCE and blood pressure variability in essential hypertension（EH）. Methods A total of 410 patients with grade 1 and grade 2 EH voluntarily participated in this study. Blood pressure was self-measured at home for one week. Based on home blood pressure（HBP） and office blood pressure（OBP）, the subjects untreated were divided into white coat hypertension（WCH, n=38） and sustained hypertension（SHT, n=66）; and the treated subjects were grouped into sustained controlled hypertension（SCH, n=131）, white-coat uncontrolled hypertension（WCUH, n=95）, masked uncontrolled hypertension（MUCH, n=16）, and sustained uncontrolled hypertension（SUCH, n=64）. And the subgroup analysis was performed in the treatment hypertensives whose diagnosis based on blood pressures inside and outside the clinic. Results（1）WCH and WCUH patients accounted for 36.5%（95%CI 27.2%-45.8%） and 31.0%（95%CI 25.8%-36.2%） respectively in this population while only acconted for 21.7%（95%CI 14.5%-28.9%） in hypertensives whose diagnosis based on OBP and out-of-office blood pressure（BP）, which was significantly lower than that based on OBP alone（34.5%）.（2）The WCE, that was, the difference between OBP and HBP, in the WCH patients was significantly stronger than SHT patientsΔsystolic blood pressure/Δdiastolic blood pressure:（22.6±9.7）/（15.0±6.6） vs（10.4±8.7）/（6.6±5.5） mm Hg, t=6.64 and 6.97, both P＜0.05, and stronger in the WUCH group compared to SCH and SUCH groupsΔsystolic blood pressure/Δdiastolic blood pressure:（25.2±9.9）/（10.7±7.2） vs（7.1±9.9）/（4.5±7.3） and（8.1±9.4）/（6.1±8.2） mm Hg, F=105.4 and 19.39, both P＜0.05.（3）Home systolic blood pressure variability（HSBPV） exhibited decreasing trends in the WCH and WUCH patients compared with SHT and SUCH patients. Conclusions The incidences of WCH and WUCH are high in grade 1 and grade 2 hypertensive patients. However, the incidence of WUCH decreases in treated patients diagnosed with OBP and out-of-office BP. Relative to other patients, WCH and WUCH patients experience stronger WCE and exhibit a decreasing trend of blood pressure variability.