Among the selection procedures applied to increase the oil content of corn grain, seems that some morpho-logical changing takes place during the process and a reduction in kernel weight can be detected. One reason to explain this situation is that inherent with the net balance disturbance between oil and carbohydrate content in the grain. The purpose of this work was to evaluate the changing in kernel weight, volume and density done by the selection procedure applied among and within half sib families in order to increase the yielding and the germ size. Seeds of S1 ears from the Original and High Oil population were used. The selection procedure did not reduce the 100 kernel weight and volume but a tendency to increase these characteristics in the High Oil population was found. A certain degree in reduction was detected for kernel density. This was done because the method of selection used in the High Oil population had a greater efficiency to increase the kernel volume than that for kernel weight.