Summary. A 24‐year‐old male was admitted to Kansai Medical University Hospital, complaining of fever, skin exanthema, jaundice, brown urine and lymphadenopathy. The patient was diagnosed as having haemolytic anaemia caused by a cold agglutinin following rubella infection. The cold agglutinin of the patient reacted strongly with group OI red blood cells (RBC), Oi cord RBC, Oi adult RBC and neuraminidase‐treated RBC, and much weaker with protease (papain, ficin, bromelin)‐treated RBC; it was identified as anti‐Pra. Cold agglutinins of anti‐Pra specificity following rubella infection in adults have rarely been reported.

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