Three weeks after a surgical operation, a 74-year old woman was admitted to hospital for severe haemolytic anaemia. A strongly positive IgG type direct Coombs test pointed to a iatrogenic origin, but a search for anti-molecule antibodies directed against all medicines taken by the patient after surgery was negative. We extended our immunological investigations and were able to demonstrate the presence of IgG type antibodies directed against an ex vivo metabolite of glafenine.