Slotless windings are commonly used in small size high-speed electrical brushless DC machines. Unlike slotted windings, forced to follow slots direction, slotless windings can be freely arranged in the airgap. This represents several opportunities for optimization. Nevertheless, very little research is performed in this domain. The present paper intends to investigate the optimization of a given slotless winding leading to a significant increase of its performances. Indeed, by optimizing the shape and by selecting non-constant wire sections, the motor constant can be theoretically increased by 24 %.