A hearing aid with a child-proof battery compartment includes a shell and a battery door mounted in the shell for rotational movement between an open position and a closed position. A latch mechanism between a pivotal latch of the battery door and a corresponding arrest part is at an internal side of an arrest wall. The battery door in the closed position includes external wall parts facing away from the hearing aid and all of the external wall parts are flush with or recessed with respect to adjacent wall parts of the hearing aid shell, such that an opening force cannot be applied to the external wall parts. The arrest wall includes a narrow gap opening which grants access to the pivotal latch and allows an opening force to be applied to the pivotal latch through the opening to release the battery door.