Drug-induced agranulocytosis is a rare, potentially fatal idiosyncratic reaction that can occur unpredictably with a wide variety of drugs when taken in a conventional dose. In this article, we discuss its diagnosis and management and we consider the drugs most commonly involved and ways of minimising risk. We do not consider the dose-related granulocytopenia that commonly complicates treatment with cytotoxic and other myelosuppressant drugs, nor the rarer reaction, aplastic anaemia.