The coffee plantation in the State of S. Paulo is usually started by putting together four, six, eight or even more plants in each pit (cova). This practice makes difficult any regular system of prunning. The elimination of some lower primary branches to promote better development of the main stem and upper primary branches to increase the yield is customary among some of our farmers. In 1932 the Coffee Department of the Instituto Agronômico (Campinas) decided to start an experiment to determine the effects of such kind of prunning on the production of coffee trees. Coffea arabica L. var. typica Cramer was- the variety choosed for the test. Five series of plants two years old (one year after transplanting to the definite place) had their lower branches suppressed for the first time and five other series were left as control, i. e,. without prunning. Both series were planted in the open at the Central Experiment Station at Campinas. The prunning was repeated every year in order to maintain the main stem of the developed tree up to the height of 40-50 cm from the ground free of primary branches. The same procedure was used for suckers in cases when they were left in order to maintain the shape of the coffee tree. The results of the first ten years (1935-1944) of experimentation show that a difference was noticed in the yield capacity of both series. Just in a single year (1944) the production of the prunned series was higher than the control. It remained lower in all the other years. The differences in the total production between both series was statistically significant (P = 1.%). The fruits in the prunned series seemed to ripe earlier than the unprunned, the size of the beans remaining constant in both treatments. In the light of the above mentioned results we infer that the practice so long used by some of our farmers is not advisable since it leads to a decrease in yield.