Computed tomography (CT) seems to be the best imaging modality to diagnose an enterovesical fistula, but is not always able to demonstrate enterovesical fistula itself. In this case report, we present Tc-99m HMPAO white blood cell (WBC) scintigraphic findings of an enterovesical fistula complicating Crohn's disease. A 22 year-old male presented with a one-month history of urinary symptoms such as dysuria, hematuria, and frequency. The patient had intermittent right lower quadrant pain, diarrhea and hematochezia. Enterovesical fistula was highly suggestive in pelvic CT which showed air density in the urinary bladder, but cystoscopy failed to find an opening of the fistula. Tc-99m HMPAO WBC scintigraphy for evaluation of inflammatory bowel disease incidentally demonstrated enterovesical fistular tract. Crohn's disease was later confirmed by histologic examination of the surgical specimen. In our patient, Tc-99m HMPAO WBC imaging was helpful in determining the location of the fistula as well as assessing the disease activity and extent of the Crohn's disease. (Korean J Nucl Med 2000;34:99-105)