Educated at the University of Ghent, Belgium, where he graduated MD with a thesis which enabled him to take the special degree of Doctor in Surgical Science. He became head of the Surgical Service at the Civil Hospital at La Bilogue in 1907. During the Balkan War in 1913 he volunteered for service in Serbia and was placed in charge of an ambulance at Belgrade. He visited the United States in 1914 immediately before the Germans invaded Belgium, and on his return was given a Commission as Colonel and appointed head of the Hoogstaede Hospital, which received a very large number of the seriously wounded as it was the nearest base hospital to the front line. The results of his experience appeared in a *Manuel de Chirurgie de Guerre*, which quickly ran through two editions. On the conclusion of peace Willems was called to fill the Chair of Clinical Surgery at the University of Liege. He died in January, 1930, and was buried at Brussels on Jan 21st, having married twice. Willems was a good surgeon and an excellent organizer. He advocated continuous extension in the treatment of fractures of the thigh in 1920; elevation of the arm after amputation of the breast in 1922; operative treatment in tuberculous diseases of the joints in 1925; and in the same year he wrote on the after-results of treating joint lesions by immediate and active mobilization. For many years he edited the *Archives Internationales de Chirurgie*, which was discontinued on the outbreak of the European War in 1914, and he was instrumental in aiding the Bruxelles-Médical from its foundation in 1920 until his death. In 1902 he was President of the Société Belge de Chirurgie, and was instrumental in founding the Société Internationale de Chirurgie, which, from small beginnings, soon became an important surgical society. For several years it held biennial meetings in Brussels and maintained a permanent bureau at The Hague. Of this Society Willems was the Hon Treasurer, and in 1926 the President at the Rome Meeting. Amongst other honours, Willems was an Hon Fellow of the Royal Society of Medicine in London, a corresponding member of the Academy of Medicine of Paris, a Commander of the Order of Leopold and of the Crown in Belgium and of the Order of the Crown in Italy; he was a Grand Officer of the Order of St Sava, a Chevalier of the Legion of Honour in France, and he held the Croix de Guerre.