[Leukopenia with unclear fever].

We report on a 77-year-old male patient with neutropenic fever as a result of a newly diagnosed agranulocytosis. The patient was taking metamizole, which is a well known cause of agranulocytosis. The diagnosis of metamizole-induced agranulocytosis as an underestimated side-effect of metamizole could be confirmed by a bone marrow biopsy. The bone marrow and the blood count recovered completely after stopping the therapy with metamizole and administration of granulocyte colony-stimulating factor (G-CSF).