Idiopathic thrombocytopenic purpura (ITP) is often diagnosed in the elderly (age >or=65 yr), where it generally presents as a chronic disease. The objective of the present study was to describe the natural history of ITP in the elderly and to evaluate the risk of bleeding and the possible occurrence of other pathologies. We retrospectively evaluated 178 ITP patients (82 men, 96 women; mean age: 72 yr) diagnosed between 1981 and 1998. Therapy was started at diagnosis or during follow-up, depending on the platelet count and/or bleeding events. Sixty-six out of one hundred and seventy-eight patients (37%) initiated therapy at diagnosis; whereas in 11 of the 112 untreated patients (9.8%) therapy was necessary during the follow-up. Low-dose of prednisone was the first-line treatment in all patients (mean daily dose of 0.43 mg/kg). Forty-nine (63.6%) of the seventy-seven treated patients showed a response, 14 of these (28.6%) suffered a relapse. Another pathology occurred in 19 of the 178 patients (10.7%). We conclude that low-dose prednisone is an appropriate initial treatment for elderly persons. We also stress that an adequate follow-up is advisable, given that isolated thrombocytopenia could in some cases be the first sign of another underlying pathology.