The Medical Defence Union (MDU) is the largest medical defence organisation (MDO) in the United Kingdom, and is one of three major MDOs in the country offering indemnity for clinical negligence claims for its members. The MDU was established in 1885 and was the first of its kind in the world. Members are doctors, medical students or other healthcare professionals; the MDU provides legal support should their clinical competence be questioned. It used to have members outside the United Kingdom, including in Singapore and Hong Kong, but withdrew from these commitments in the late-1990s.