We report a case of primary plasma cell leukaemia, with an absolute count of plasma cells of 53 Giga/L, diagnosed in a 83-year-old woman. The patient's condition improved, with no circulating plasma cells after 3 weeks of treatment, in response to the combination of thalidomide and dexamethasone administered for 5 days followed by thalidomide alone. The clinical presentation, the morphological, flow cytometric and pathophysiological characteristics of the plasma cell leukaemia and the treatment are summarised in this paper.