Three embodiments of flexible covers for an ultrasound probe are disclosed. The first embodiment comprises a flexible sheath applied with a ring applicator and elastic bands. The second embodiment comprises a flexible sheath applied with a dual-walled foldable applicator. The third embodiment comprises a folded-over flexible sheath which is then rolled, incorporating in the roll a flexible band. Each of the embodiments is designed to facilitate easy application of a sterile sheath over an ultrasound probe.