Drug-induced cytopenias are sometimes related to the so-called immuno-allergic mechanism which involves an unusual and unpredictable (i.e.: allergic) immune mediated reaction against the drug, leading to the cell-lysis of either peripheral blood granulocytes, thrombocytes; or erythrocytes. Agranulocytosis is typically induced by amidopyrine, whereas thrombocytopenia and hemolytic anemia are observed with drugs like quinine-quinidine, betalactams antibiotics, sulfonamides, rifampicin etc. In vitro methods for identification of the offending drug are cumbersome and poorly suitable for routine use. Therefore, definite diagnosis in these cases is first based on clinical and hematological grounds. These accidents recover spontaneously. However, potentially severe complications (infection, bleeding) deserve to prevent the risk of recurrence by a lifetime prohibition of the identified or suspected drug.