Increased left ventricular (LV) mass (M) in children with chronic renal insufficiency (CRI) might represent an adaptive mechanism to compensate for increased workload. We hypothesized that in children with CRI, pre-dialysis, values of left ventricular mass (LVM) exceed compensatory values for individual cardiac load. Complete anthropometric characteristics, biochemical profile and echocardiograms were obtained for 33 children with CRI, pre-dialysis (age 1-23 years, mean 12.2 +/- 5.0 years), and 33 age- and gender-matched healthy controls. LV dimensions, wall thicknesses and volume were measured. Endocardial and midwall shortening, ejection fraction, LVM, LVM index, relative wall thickness, circumferential wall stress and excess LVM (as ratio of observed LVM to value predicted from body size, gender and cardiac workload) were analysed. Patients with CRI showed higher values of LVM index, resulting in higher prevalence of LV hypertrophy (36.3% vs 9%, P < 0.05). The ratio of excess LVM was greater in patients with CRI than in healthy controls (126 +/- 19% and 103 +/- 13%, respectively, P < 0.001). LV ejection fraction, midwall fractional shortening and stress-corrected midwall shortening were lower in patients with CRI than in controls. We concluded that, in children with CRI, the values of LVM are higher than those needed to sustain individual cardiac load than in healthy controls, a condition associated with LV hypertrophy and reduced systolic performance.