This study was conducted at the C.N.!. Tibaitata in 1980, to determine the effect of divergent mass selection for ears per plant on internode pattern of two subpopulations derived from the synthetic Harinoso Mosquera I Sin.2. The results corresponded to the selection cycles from 12 to 20 of each subpopulation. Arando. mized complete block design with 22 treatments, 10 blocks was used. From each plot a random sample of ten plants were taken and the following characteristics were measured: number of internodes, interhode lenght and number of internodes above and below the upper ear. The internode patterns allowed to analize in a integral way, the changes in the characteristics considered: the plants of the prolific subpopulation were higher because they had more and longer internodes than the non-prolific population. The increase of the internode number ocurred below the upper ear. It was also observed that the internode patterns of the non prolific population, were similar to the original variety. Therefore, the response to mass selection to increase prolificacy, was accompanied with a collateral response in the number and lenght of the internodes.