We report the case of a relatively young man with multiple and fatal thrombosis associated with essential thrombocythaemia. The clinical and laboratory examinations performed before his death were in agreement with the diagnostic criteria proposed by PVSG. The autopsy revealed myocardial infarction and pulmonary embolisms. This case suggests that young patients with primary thrombocytosis should be treated with antiplatelet agents in spite of the absence of other thrombotic risks.