The impact of learning on brain functional laterality has not been systematically investigated. We employed an event-related functional magnetic resonance imaging combined with a delayed sequential movement task to investigate brain activation pattern and laterality during a transient practice in 12 subjects. Both hemispheres, involving motor areas and posterior parietal cortex, were engaged during motor preparation and execution, with larger activation volume in the left hemisphere than in the right. Activation volume in these regions significantly decreased after a transient practice, with more reduction in the right hemisphere resulting increase in left lateralization. The theoretical implications of these findings are discussed in relation to the physiological significance of brain functional laterality.