The proportional area of each renal arterial segment was analyzed in 49 polyester resin corrosion endocasts of the renal vasculature. We defined a segmental artery as a primary or secondary branch of the renal artery that could be isolated outside the hilum. We found kidneys with five arterial segments in 30 of 49 casts (61.2% of cases) and kidneys with four arterial segments in 19 of 49 casts (38.8%). To enable the evaluation of the proportional areas of the autonomous segments (by using the "point-counting planimetry method"), each arterial segmental branch was injected with different-colored resin. The superior segment (apical) was present in 36 of 49 casts (73.5% of cases) and had a median proportional area of 13.02%. The anterosuperior and anteroinferior segments were present in 30 of 40 casts (61.2% of cases) and had median proportional areas of 21.36% and 17.18%, respectively. The anterior segment was present in 19 of 49 casts (38.8% of cases; when the mid-kidney anterior surface received only one segmental artery) and had a median proportional area of 28.44%. The inferior segment was present in 100% of cases and had a median proportional area of 22.65%. The posterior segment was also present in 100% of cases and was the segment with the greatest median proportional area (33.76%).