Background: We evaluated the prevalence of left ventricular hypertrophy in elite footballers compared with sedentary controls. A total of 141 elite male professional footballers and 32 healthy sedentary controls were studied. Echocardiographic and demographic variables were compared between groups by unpaired t-test. Results: The prevalence of left ventricular hypertrophy with:maximal wall thickness values outwith the normal range (>12 mm) was noted. Footballers were significantly younger than controls (20.9 vs. 24.3 years, P<0.005: 95% CI (-5.2, -1.73)) but there were no significant differences in height, weight or body surface area between the groups. Each of inter-ventricular septum (10.4 vs. 9.1 mm, P<0.0001; 95% CT (0.88, 1.72)), posterior wall (9.2 vs. 8.5 mm, P<0.01; 95% CI (0.22, 1.21)), left ventricular cavity (systolic and diastolic) (34.5 vs. 28.4 Mn, P<0.0001; 95% CI (4.31, 7.76) in systole; 50.1 vs. 48.2 mm, P<0.05; 95% CI (0.15. 3.74) in diastole), aortic root size (29.1 vs. 27.8 mml P<0.05, 95% CI (0.03,2.49)) and left ventricular mass index (112 vs. 89 g/m(2), P<0.0001; 95% CT (14.4, 32.1)) were significantly greater in footballers than in controls. Absolute left ventricular wall thickness >12 mm was present in 17 footballers (12%) (range 13-15 mm) and in no controls. Conclusions: Elite professional footballers have increased cardiac dimensions compared with healthy controls. The prevalence of absolute wall thicknesses outwith the normal range is relatively high. (C) 1999 Elsevier Science ireland Ltd. All rights reserved.