A sterile enclosure is provided for enclosing a hand-held ultrasound device to prevent any material on the ultrasound device from contaminating a sterile environment in which the ultrasound device is used. The enclosure has an opening for insertion of the ultrasound device into the enclosure, a closure for closing the opening, an acoustically-transparent transducer portion for covering an active face of a transducer of the ultrasound device, and a transparent display portion overlaying a display of the ultrasound device. In some embodiments a detachable or integrally formed needle guide is provided with the enclosure, for holding and guiding a needle so that the needle is projected into a field of view of the transducer of the ultrasound device.