An expert system on nursing diagnoses related to urinary elimination, according NANDA's taxonomy, was developed and evaluated. Data were collected using a form and a checklist of defining characteristics. The obtained consensus diagnoses by three specialists were considered gold standard. 197 cases were tested. The system proved to be adequate for determining diagnoses such as 'stress urinary incontinence', 'urge urinary incontinence', 'urinary retention' and 'total urinary incontinence' with sensitivity and specificity above 98%. The accuracy evaluation in relation to 'impaired urinary elimination', 'reflex urinary incontinence' and 'functional urinary incontinence' was not possible to be established due to the small size of the sample. The experience in developing and evaluating this program can be applied in creating other expert systems.