A cover for a probe 12, such as an ultrasonic probe, the cover comprising a flexible elongate pouch 1 and a mouth portion 2 for inserting the probe 12 into the pouch, the mouth portion 2 comprising sealing means to enable the mouth portion to be formed into sealing engagement with a proximal end 11 of the probe. Also, a method of preventing a decontaminated ultrasonic probe from contamination comprising the step of, immediately after disinfection, inserting the ultrasonic probe 12 into a cover comprising a flexible elongate pouch 1 and a mouth portion 2 for inserting the probe 12 into to pouch, the mouth portion 2 comprising a deformably rigid portion 3, and deforming the mouth portion 2 into a sealing engagement with a proximal end 11 of the probe, wherein no undisinfected portion of the probe 12 enters the pouch 1.