An arrangement of a tank of lubrication liquid for an aircraft turbomachine, under a nacelle cowling covering the turbomachine, is provided. The tank is arranged in the volume located between the turbomachine and the nacelle cowling. The nacelle cowling includes an opening for access to the volume. The tank is fastened to an internal face of a panel closing off the opening. The unit formed by the panel and the tank is added onto the nacelle cowling and is able to be mounted and dismounted from the nacelle cowling.