Many hypertensive patients affected by endogenous Cushing's syndrome (CS) persist with high blood pressure (HBP) despite good control of cortisol excess. We assessed the effect of preoperative ketoconazole administration and of definitive treatment of CS on arterial hypertension and analysed the factors involved in the persistence of hypertension. We assessed retrospectively 71 patients with CS and HBP (60 women, 11 men; 50 pituitary, 21 adrenal) successfully treated by surgery and/or radiotherapy; 19 of them received ketoconazole (KNZ) before surgery. After treatment, patients were divided into those with persistent high blood pressure (PHBP) and those with normal blood pressure (NBP). As possible predictive factors for PHBP we analysed age, duration and family history of HBP, pre-treatment 24 hour urinary free cortisol (24h-UFC) and body mass index (BMI). HBP normalized in 53 out of 71 patients (74.6%), regardless of the origin of Cushing's syndrome. PHBP patients were older (p=0.003), had longer duration (p=0.007) and higher systolic blood pressure before treatment (p=0.046) than NBP patients. Thirteen out of 19 patients (68.4%) treated with ketoconazole, normalized their hypertension and remained normotensive after successful surgery. Five patients became normotensive only after surgery. In conclusion: a) blood pressure levels normalized in most patients after remission of CS; b) ketoconazole was effective for the control of HBP, and seems to be a good indicator of post-surgical outcome, and c) higher age at presentation, longer duration of hypertension and higher systolic blood pressure figures before treatment negatively influence normalization of blood pressure after resolution of Cushing's syndrome.