The results of topping 15 seedlings of rubber tree (Hevea brasiliensis Muell.-Arg.) approximately 30 years old are presented. The tapping system adopted was an half-spiral cut, tapped every other day in the morning. The initial height of opening the tap was one meter above the soil, the cut made at an angle of 30° counterclockwise downward. After the results were collected, the length of the cuts was measured and as it was observed that almost all cuts were much shorter than they should be, a correction was introduced, based in the girth of the trees and their respective daily production expressed in cc of latex per cm of length of cut. The best plant yielded 35% of the total production of 10 plants studied from March 16, 1943 to September 30, 1944. The study of the plants as a group presents the following results: a) 10% of the plant population yielded 35% of the total latex production; b) 50% of the plant population yielded 79% of the total latex production; c) 70% of the plant population yielded 90% of the total latex production. The data confirm that in order to find out the best yielding plant of a group of unselected seedlings it is not necessary to tap the trees for a long time; after a few tappings the high yielding plants are revealed.