We present a rare, but increasingly recognised, cause of thrombocytopenia in a 69-year-old Caucasian female. Complete haematological investigation, including blood films and autoantibody screen, did not reveal a cause for her thrombocytopenia. Omission of potentially offending medication did not improve the low platelet count. She had no features of systemic infection or inflammatory disease on history and examination. In light of persistent thrombocytopenia, Helicobacter pylori stool antigen was tested, and found to be positive. Platelet count improved after eradication therapy for H pylori. This prevented the need for steroid and immunoglobulin treatment in this patient.