In order to study the echocardiographic abnormalities in consecutive patients with malignant phase hypertension (MHT), we reviewed echocardiograms of 31 patients (23 male; mean age 52+/-14 years) with MHT who were admitted to our unit. Trans-thoracic echocardiography was carried out in all patients, and echocardiographic measurements were compared with those of 39 patients (30 male; mean age 54+/-10 years) with controlled nonmalignant essential hypertension, and 32 (19 male; mean age 51+/-10 years) healthy normotensive volunteers. Patients with MHT had a significantly higher mean systolic and diastolic blood pressure (P<0.001) compared to the other two groups. MHT patients had significantly greater mean left atrial dimensions (P=0.002), as well as aortic root dimensions (P=0.01) and left ventricular (LV) dimensions (with the exception of the diastolic internal diameter) (P<0.001). MHT patients also had a mean larger LV mass and LV mass index (both P<0.001) when compared to the other two groups. The mean ejection fraction was also lower in the MHT group (P<0.001). In conclusion, patients with MHT have significant cardiac hypertrophy, in association with systolic dysfunction and dilated left atria, irrespective of the duration of known hypertension. These abnormalities may predispose MHT patients to cardiovascular complications including heart failure and cardiac arrhythmias, such as atrial fibrillation.