Abstract: The invention provides an assembly for anorectal manometry, comprising a manometer (10, 210, 410) and a sheath (14) which provides a barrier against contamination of the manometer with foreign matter, and hence a precaution against transmission of infection. The manometer comprises a probe (12, 212, 212) comprising a proximal portion (264b) and a distal tip portion (264a), the probe being insertable through an anus so that the distal tip portion extends into the rectum, and the probe being provided with a plurality of proximal pressure sensors (40, 164, 240) responsive to pressures applied to the proximal portion of the probe. The sheath is formed to receive the probe and to provide a continuous covering over at least the proximal portion and the distal tip portion of the probe.