“…Those most commonly described are cold agglutinins, either non-specific (Ellis, Wollenman, and Stetson, 1948;Green and Goldenberg, 1960;Fekete and Kerpelman, 1965) or with anti-i specificity (Rosenfield, Schmidt, Calvo, and McGinniss, 1965;Jenkins, Koster, Marsh, and Carter, 1965;Calvo, Stein, Kochwa, and Rosenfield, 1965;Troxel, Innella, and Cohen, 1966). A number of patients have been investigated fruitlessly for cold haemolysins of the Donath-Landsteiner type (Green and Goldenberg, 1960;Kostinas and Cantow, 1966); only one case of infectious mononucleosis with haemolytic anaemia and a positive Donath-Landsteiner reaction has actually been recorded (Ellis et al, 1948). This paper presents a second case Received for publication 28 February 1973. of this association occurring in the absence of syphilitic infection.…”