Background Chronic kidney disease (CKD) is one of the common causes of renal failure. Renal sonography is an essential diagnostic tool in nephrology. Renal sonographic dimensional parameters could be of great utility, providing indirect but valuable information about the morphostructural changes occurring in the kidney in the course of CKD. Aim To determine whether there is a relationship between renal cortical thickness and renal length measured on ultrasound and the degree of renal insufficiency in patients with CKD. Patients and methods From December 2016 to October 2017, 50 patients with clinically stable chronic renal insufficiency participated in this study. Renal sonographic parameters including length of the kidney, cortical thickness, and renal echogenicity were measured. Serum creatinine was used for estimated glomerular filtration rate using Cockcroft and Gault equation for all patients. Results The most common cause of CKD in our patients was systemic lupus (22%) followed by hypertension (16%). The mean renal length was 97.6 ± 12.2 mm, the mean cortical thickness was 9.38 ± 1.79 mm, the mean serum creatinine level was 2.46 ± 1.74 mg/dl, and the mean value of estimated glomerular filtration rate using Cockcroft and Gault equation was 60.95 ± 53.78 ml/min. There was a high statistically significant relationship between cortical thickness and creatinine clearance (r = 0.67,P Conclusion Renal cortical thickness measured at ultrasound appears to be more closely related to the degree of renal impairment in patients with CKD than renal length.