Abstract: AIM:To explore the association between morning blood pressure surge and changes of blood pressure after cold pressure test in prehypertensive patients. METHODS: According to blood pressure levels, 258 subjects were divided into three groups, namely, normotensive group, prehypertensive group and hypertensive group. Twenty-four hour ambulatory blood pressure monitoring and cold pressure test were conducted in all subjects. RESULTS: Morning blood pressure surge was (27±9) mmHg and the increased amplitude of systolic blood pressure at 0 and 60 sec after cold pressure test was (14±6) mmHg and (9±5) mmHg, respectively. The rate of positive morning blood pressure surge and cold pressure test was 45% and 26% in prehypertensive group, lower than that in the hypertensive group but significantly higher than that in the normotensive group (P<0.05). Morning blood pressure surge, smoking history, age and high-density lipoprotein were important factors for the increased amplitude of systolic blood pressure at 0 sec after cold pressure test. Morning blood pressure surge, age and fasting plasma glucose were important factors for the increased amplitude of systolic blood pressure at 60 sec after cold pressure test. CONCLUSION: Sympathetic nervous system activity was enhanced in prehypertensive patients. Blood pressure was significantly elevated in the morning and after cold pressure test in prehypertensive patients. Increased amplitude of blood pressure after cold pressure test is associated with morning blood pressure surge in prehypertensive patients.