As a standard method for the measurement of post-void residual urine volume, the urethral catheterization is commonly used. However, it is frequently associated with the discomfort of the patients, urethral trauma and urinary tract infection. A noninvasive method of determining the residual urine volume could minimize unnecessary catheterizations and be useful in the management of neurogenic bladder in the patient with spinal cord injury(SCI). This study was undertaken to evaluate the accuracy of a portable ultrasound scanner for measuring bladder volumes in SCI patients undergoing bladder training and to determine the factors affecting its accuracy. Sixty patients with SCI were included in this study. Two investigators performed the ultrasound measurement of the post-void residual urine volume alternately and the same procedures were repeated. After that, the urethral catheterization was done. In comparison of the residual volume measured by two different methods, the correlation coefficient(R²) of the two different methods was 0.996 and the mean value of difference between the residual volume measured by ulltrasound and by catheterization was 21.6 ml. The accuracy of the ultrasound measurements was not affected by gender, types of the neurogenic bladder, shape of the bladder, trabeculation of the bladder and central obesity. The results indicate that the portable ultrasound scanning method is a useful non-invasive method and can be substituted for the urethral catheterization in determination of bladder volumes in patients with SCI.