This research aimed to analyze the clinical data of various etiologies of hypertension in patients hospitalized in the Endocrinology Division. The differences between essential and secondary hypertension were examined to provide a basis for clinical differential diagnosis. The data from all the inpatients with hypertension of unknown origin admitted in the Endocrinology Division of the First Affiliated Hospital of the Zhejiang University School of Medicine from January 2001 to May 2011 were reviewed. The patients were classified into either essential or secondary hypertensive groups. The differentiating parameters of these forms of hypertension were analyzed using the one-factor and multi-factor logistic regression analysis. A total of 1,001 cases were selected in which 346 cases (34.6%) were essential hypertensive and 655 cases (65.4%) were secondary hypertensive. Adrenal hypertension was the primary cause of secondary hypertension, followed by renal artery, central, psychogenic, and renal hypertension as well as others that have not been classified systematically. Using one-factor analysis, significant differences were found among duration of hypertension, age, the onset age, family history of hypertension, diastolic pressure on admission, Cushing syndrome, body mass index (BMI), urine protein, serum creatinine, orthostatic aldosterone, ratio of orthostatic aldosterone to renin activity, incidence of fatty liver displayed by type-B ultrasound, and computed tomography adrenal masses incidence (P < 0.05). Multi-factor regression analysis showed that family history of hypertension (OR = 7.196) and BMI above the normal range (OR = 15.124) were the independent factors that predicted essential hypertension, but failed to determine any other valid predictors of secondary causes except adrenal masses (OR = 10.114), orthostatic aldosterone value >200 pg/ml (OR = 9.742), and a ratio of orthostatic aldosterone and renin activity >40 (OR = 4.723).