Cyclic thrombocytopenia (CTP) is a rare disorder characterized by periodic decreases and increases in platelet levels. Each cycle usually spans a period of 3-5 weeks. Clinical features are similar to those of idiopathic thrombocytopenic purpura (ITP), so patients are frequently misdiagnosed as having ITP. However, CTP usually does not respond to most treatments used in ITP such as corticosteroids, splenectomy and intravenous immunoglobulin. In this case report, we present a 33-year-old woman with CTP misdiagnosed as ITP.