Renal ultrasound appearances have been examined in 315 patients with sickle cell disease aged 10-20 years, followed in a cohort study from birth. There were three different echo patterns. A normal appearance (type 1) occurred in 235 (75%) of all subjects, and in 159/179 (89%) with homozygous sickle cell (SS) disease. A diffuse increase in reflectivity throughout the kidney (type 2), similar to that of adjacent liver, occurred in 17 patients (5%). Widespread confluent or focal increase in reflectivity confined to the renal medulla (type 3) occurred in 63 (20%) of the total group, and was much more common in the mild genotypes of sickle cell-haemoglobin C disease (41/111, 37%) and sickle cell-beta+ thalassaemia (15/19, 79%) than in SS disease (5/179, 3%). We speculate that type 2 changes may reflect diffuse glomerular and interstitial fibrosis, and that type 3 resembles changes seen in sub-clinical nephrocalcinosis, and could be due to iron deposition.