Ali Krogius was born at Helsingfors on 7 November 1864. From 1889 he worked in the Guyon Clinic at Paris on the bacteriology of urinary infections, publishing his identification of *B coli* in the urine as his MD thesis at Helsingfors in 1892. During 1890-94 he was assistant in the surgical clinic there, becoming lecturer in surgery in 1893. He was employed by the government in the suppression of an outbreak of cattle haematuria in 1893-94 and of a cholera epidemic in 1893. In 1901 he succeeded M W of Schulten as professor of surgery and took over the new surgical clinic, which was the only modern hospital in the whole of Finland. His lectures on surgical diseases of the urinary organs, published in Swedish in 1898, reached a fourth edition in 1930 and is a standard work throughout Scandinavia. His interest gradually shifted from bacteriology to pathological anatomy. Though chiefly concerned with urinary diseases he also wrote on abdominal, plastic, and nerve surgery. He published a study of cocaine-analgesia in *Zentralblatt für Chirurgie*, 1894, 21, 241; this was a pioneer work in what he called "regional anaesthesia", but he did not follow it up. After Schulten's unexpected death his energies were entirely occupied with operating and teaching, at both of which he was a master. During 1901-04 he took a leading part in the appendicitis controversy, and by his practice and writings did much to establish the early operation in Finland and to bring the controversy to a peaceful conclusion in the North. Retiring as emeritus professor in 1929, he studied hypertrophy of the prostate, and resumed private practice. He also developed an interest in the history of medicine, and wrote accounts of his predecessors in the professorship and a remarkable study of Napoleon. His last work was a history of surgery in Finland. He died on 12 May 1939, aged 74. He received many honours, of which he valued most the Honorary Fellowship of the College conferred at the Lister centenary, and the Honorary Doctorate of Upsala at the 450th anniversary of the University, both in 1927. He was an active member of the Finska Lakaresallskapet and of the Deutsche Gesellshaft für Chirurgie. He was beloved by his family and friends, and esteemed by his colleagues not only for his professional ability and great natural gifts but for his character and cultivation.