Reciprocal full-sib selection (FR) for yield improvement was conducted in the BS 10 and BS 11 maize (Zea mays L.) populations. Our objectives were to evaluate the effects of six cycles of reciprocal full-sib selection in BS 10 and BS 11 and to determine what changes had occurred in the magnitudes of additive and dominance variance resulting from six cycles of selection. Grain yield of full-sib progenies increased 6.3 percent in BS 10 and 5.7 percent in BS 11 from CO to C6. Grain yield of S₁ lines increased 11.6 percent in BS 10 and 26.3 percent in BS11 from C0 to C6. Estimates of additive genetic variance suggested a decrease from the C0 to C6 of BS 10 and BS 11 for yield and stalk lodging and an increase for ears per plant from BS 10C0 to BS10 (FR) C6. Estimates of dominance variance generally increased, but decreases were observed for yield and stalk lodging in BS11. The changes in the estimates of genetic variances suggest genetic variability was reduced with selection but most of the changes were small and statistically nonsignificant.