FROM 1882, when Friedl盲nder1 described a micro-organism which he believed was the causative agent of lobar pneumonia, to recent times, infections with Klebsiella pneumoniae were thought to be almost wholly concerned with pathologic changes of the lungs. This concept of Klebsiella infection underwent a change following the report of Baehr, Shwartzman and Greenspan2 in 1937. In a study of 198 cases of Friedl盲nder's infections, these workers were able to establish a definite diagnosis of primary infection of the respiratory tract in only 2 cases. In approximately 80 per cent of their patients the primary sites of infection were the gastrointestinal tract, the genitourinary tract and the biliary passages and liver. So impressed were these investigators by the paucity of primary respiratory infections caused by this organism that they proposed a change of the name from Klebsiella pneumoniae to Klebsiella friedl盲nderi. Since 1937 there have been a number of