Antithrombotic therapy related thrombocytopenia has been extensively described concerning heparin and ticlopidine therapy.Clopidogrel is frequently associated with thrombotic thrombocytopenic purpura however this drug is rarely related to severe isolated thrombocytopenia.To the best of our knowledge, pentoxifylline was associated with thrombocytopenia only once.We report the first case of severe isolated thrombocytopenia after therapy with both clopidogrel and pentoxyfilline.A 79-year-old caucasian man presented to his general physician with intermittent claudication.He had obliterative arterial disease, therapy with clopidogrel and pentoxifylline was started and he was referred to a vascular consult.The basal platelet count was 194x 109/L.Three days after the therapy beginning, the patient had lower limb petechia and stopped taking clopidogrel and pentoxifylline.On the 17th day after therapy beginning, platelet count was repeated and because it lowered to 4x 109/L the patient was admitted to the hospital, in our Internal Medicine ward.The patient had purpura, without other hemorrhages or splenomegaly.Severe isolated thrombocytopenia was confirmed (5 x 109/L),blood smear was normal and bone marrow study showed dysmegakaryopoiesis.Fibrinogen level was normal.Haptoglobin and complement were normal.Antiplatelet antibodies were negative as were all viral serologies.Imaging study was normal.Neoplasm was excluded.The patient started immunoglobulin, but there was no sustained platelet increase,so corticotherapy was the next step.Five month after clopidogrel and pentoxifyllinewere discontinued, platelet count continued increasing even after prednisolone was tapered.The patient is currently well.After platelet count returned to normal, the patient was started on aspirin with close monitoring and no significant change and continues obliterative arterial disease follow-up with the vascular surgeon.Clopidogrel and pentoxifylline are widely used by general physicians, internists, cardiologists and vascular surgeons.This report was published in the Journal of Medical Case Reports and alerts for the need to monitor platelet count in patients taking these drugs.