Background: We tried to understand whether or not there is a difference in occurrence of renal atrophy between the left and right sides in sickle cell diseases (SCDs). Methods: All patients with SCDs were enrolled into the study. Results: The study included 311 patients (153 females). There were seven cases (2.2%) with left renal atrophy against one case (0.3%) with right renal atrophy (p<0.001). Associated thalassemias were detected in 44.0% and splenomegaly in 12.5% of the patients. There was digital clubbing in 6.4%, chronic obstructive pulmonary disease in 4.8%, leg ulcers in 12.8%, stroke in 7.0%, chronic renal disease in 8.6%, pulmonary hypertension in 11.8%, cirrhosis in 3.5%, coronary heart disease in 8.0%, and exitus in 5.7% of the patients. Conclusion: Renal atrophy is significantly higher on the left side in SCDs. Splenomegaly induced flow disorders in left renal vessels, structural anomalies of the left renal vein including nutcracker syndrome and passage behind the aorta, and possibly the higher arterial pressure of left kidney due to the shorter distance to heart as an underlying cause of endothelial damage induced atherosclerosis, may be some of the possible causes. Because of the higher prevalences of left varicocele probably due to drainage of left testicular vein into the left renal vein, high prevalences of associated thalassemias with SCDs as a cause of splenomegaly, and tissue ischemia and infarctions induced edematous splenomegaly in early lives of the SCDs cases, splenomegaly induced flow disorders of left renal vein may be the most significant cause among them.