251 in stable hypertensives were studied with M-Mode and two-dimensional echocardiography, in order to evaluate the prevalence of left ventricular hypertrophy (LVH), its patterns and clinical correlates. 54 subjects (21%) had been treated previously with antihypertensive drugs while the remaining 197 (79%) had not. A normal left ventricle was found in 69 subjects (27.1%; group A); a concentric LVH (h/r greater than or equal to 0.45) was found in 99 (39.4%; group B), while an eccentric LVH (left ventricular myocardial mass index greater than 140 g/m2, h/r less than 0.45) in 83 (43.1%; group C). An asymmetric LVH (septum to posterior wall thickness ratio greater than or equal to 1.3) was found in 33 subjects (3 did not fulfill the criteria for LVH, 21 had a concentric, and 10 an eccentric LVH). Mean age was significantly higher in group B as compared to groups A and C. The body mass index was comparable in all groups. Mean systolic blood pressure was significantly higher in groups B and C as compared to A. The duration and the severity of hypertension did not differ among the three groups. W.H.O. stage III was absent in group A, but no differences were found between group B and C as for W.H.O. stage distribution. We conclude that such factors as BMI, duration and severity of hypertension poorly correlate with the occurrence of LVH and its patterns. The fact that group B hypertensives were older than the others on average is against the hypothesis that eccentric hypertrophy follows the concentric pattern. Whether these two patterns represent separate entities in relation to different hemodynamic profiles deserves further investigation.