Anatomical relationship between the renal venous arrangement and the kidney collecting system. The anatomical relationships between the renal venous arrangement and the pelviocaliceal system were studied in 52, 3-dimensional polyester resin corrosion endocasts. In 53.8% of the cases, there were 3 large venous trunks and in 28.8% there were 2 venous trunks joining to form the main renal vein. Intrarenal veins demonstrated free anastomoses that were disposed in 3 systems of longitudinal arcades (stellate, arcuate and interlobar veins). There were large venous collars around caliceal necks and also horizontal arches crossing over calices to link anterior and posterior veins. In 84.6% of the cases the upper caliceal group was encircled anteriorly and posteriorly by venous plexuses, which coursed parallel to the infundibulum. In 50.0% of the cases the lower caliceal group also was enriched by 2 venous plexuses. A close relationship existed between a large inferior tributary of the renal vein and the anterior aspect of the ureteropelvic junction in 40.4% of the cases. In 69.2% of the cases there was a posterior (retropelvic) vein: in 48.1% this vein had a close relationship to the junction of the pelvis with the upper calix and in 21.1% it crossed the middle posterior surface of the renal pelvis. 