We have observed a high incidence (36.4%) of asymmetric septal hypertrophy (ASH), detected with the use of M-mode (MME) and two-dimensional echocardiography (2DE), in normotensive patients with chronic renal failure on maintenance hemodialysis without signs of cardiac diseases. ASH was detected by conventional MME in 11 cases and was confirmed with the use of 2DE in 8 cases showing a diagnostic concordance of 72.7% between the two methods. After dialysis the MME study of the left ventricular (LV) performance showed an evident impairment of cardiac index (CI) due to reduction of LV volume in addition to an abnormality of septal function. The presence of ASH does not impair the percentage of fractional shortening (FS%), the mean circumferential shortening (mean Vcf) and the ejection fraction (EF%), probably because of a compensatory performance of the LV posterior wall. Predialysis serum creatinine and fasting triglycerides have been found significantly higher in the group with ASH. ASH may be considered as a focal and early form of myocardial involvement in uremic patients on regular hemodialytic treatment.