The incidence of prostate disease is high. However, accurate assessment of pathological conditions is still difficult. Although CT, MRI, and TRUS imaging methods provide useful information, each has specific drawbacks. Our work examines the potential and utility of 3D trans-urethral ultrasound (TUUS) for improved imaging of the prostate. Four normal canines were examined with TUUS. The catheter was placed in the urethra and used to image the prostate, rectum, bladder, ureter, neuro-vascular bundles, arteries, and surrounding tissue. 2D and 3D datasets were acquired and digitized. The 2D data provides useful visualization of the tissue. The clinician was also able to watch urine enter the bladder and perform a digital rectal exam in real-time. 3D data visualization required torodial reconstruction. The algorithm was optimized to provide very fast 3D reconstructions of the prostate. Segmentation of the data proved challenging, but 3D visualization, including volume rendered data and surface rendered data, were well accepted by clinicians. Clinicians and researchers determined a number of potential applications of these new techniques, including: prostate cancer diagnosis and staging, assessment of Benign Nodular Enlargement, assessment of physiologic function of the bladder, evaluation of morphologic properties of the prostate, and image guided biopsy and therapy.