The results of a one year tapping of 31 seedlftigs of rubber trees (Hevea brasiliensis Muell.-Arg.) approximately 33 years old are discussed. The tapping system adopted was a half-spiral cut, tapped every other day in the morning. The initial height of oppening the tap was one meter above the soil, the cut made at an angle of 30º counterclockwise downward. After the results were collected, the length of the cuts was measured. It was noted that almost all cuts were much shorter than they should be. To avoid the error, a correction was introduced based in the girth of the trees and their respective daily producion. The results show a great variability in the yield of the trees and a pronounced assymetry in the distribution of the plants based in their daily latex production; the best plant, yielded 12.07% of the total production and the worst only 0,78%. The study of the plants as a group presents the following results: a) approximately 10% of the population yielded almost 25% of the total production; b) approximately 25% of the population yielded almost 50% of the total production; c) approximately 50% of the population yielded almost 75%, of the total production. These results show that it seems possible to use unselected seeds as commercial planting material. The scedlings must be planted at very high density in the field, in order to permit the elimination of a large number of young, low yielding plants. This selective thinning will increase the average yield per plant, allowing the establishment of commercial plantations of guod yield per unit area. The data also show that, in order to find out the best yielding plants of a group of unselected seedlings, it is unnecessary to tap the trees for a long time. After a few tappings the high yielding trees are revealed. For the 31 plants studied, the results of two weeks of tapping showed the nº 8 to be the best yielding tree; the results of one year of tapping confirmed these results.