It was determined the diagnostic accuracy of sonography value in the detection of renal stones using CT as the gold standard. In addition, we correlated the accuracy of sonography with stone size, the kidney affected and body mass index (BMI). The study included fifty patients which performed sonographic examinations and after this CT scan examination was performed to confirm the diagnosis. CT scans were evaluated by one radiologist, and the diagnosis was made by consensus. We compared the sonograms and CT scans and the sonographic detection of stones in the left and right kidneys. All sonographic findings were correlated with the BMI groups. Accuracy of sonography for detection of stones in the kidney as the calculation of up to 1 cm was 71%, at 1-2 cm in size was 98.8%, and larger than 2 cm was 100% respectively for left kidney up to 1 cm 54.5%, 88.2% from 1-2 cm and 2 cm greater than 90.9%. Sonography is of limited value for detecting renal stones. The sonographic detection of a renal stone is dependent on the side of localization in the kidney and of BMI.