The dimensions of the cardiac chambers and left ventricular function were studied by echocardiography in 40 patients with homozygous sickle cell disease (SS) and 25 patients with heterozygous sickle cell trait (12 AS, 10 SC, 3 BS) and compared with the same parameters in 30 normal subjects. Patients with homozygous SS disease had significantly larger left atrial (32.2 +/- 6.47 mm vs 26.62 +/- 5.64 mm; p less than 0.001), left ventricular (46.4 +/- 8.49 mm vs 39.97 +/- 5.29 mm; p less than 0.001) and right ventricular (17.95 +/- 5.08 mm vs 15.5 +/- 3.17 mm; p less than 0.02) dimensions: they also had higher indexed myocardial surfaces (11.48 +/- 2.36 cm2/m2 vs 8.21 +/- 1.97 cm2/m2; p less than 0.001) and indexed end diastolic left ventricular volumes (101.84 +/- 22.74 ml/m2 vs 65.05 +/- 10.81 ml/m2; p less than 0.001), a higher cardiac index (4.77 +/- 1.33 l/mn/m2 vs 3.58 +/- 1.08 l/mn/m2; p less than 0.001) and stroke volume (71.77 +/- 32.86 ml vs 49.56 +/- 13.39 ml; p less than 0.001). Peripheral resistances were significantly lower (1341 +/- 469 vs 1626 +/- 368 dynes/s/cm-5; p less than 0.01) as were the velocities of circumferential fibre shortening (VCF) (1.11 +/- 0.20 circ/s vs 1.28 +/- 0.24 circ/s; p less than 0.01). Two thirds of homozygous SS disease patients (27/40) had appearances of an anaemic heart with eccentric left ventricular hypertrophy, normal left ventricular systolic function, an increased cardiac index (5.01 +/- 1.19 l/mn/m2) and low peripheral arterial resistances.(ABSTRACT TRUNCATED AT 250 WORDS)