We report a 51 years old female who had a first episode of thrombocytopenia ad 23 years of age during a pregnancy. At the age of fifty, a hysterectomy was indicated due to a metrorrhagia: a platelet count of 21000/ul was detected. She was treated with eltrombopag with a good response. A family history of the patient revealed the presence of thrombocytopenia in several family members. Suspecting a hereditary thrombocytopenia, a genetic study revealed a mutation in the MYH-9 gene. This mutation can be suspected when there is a family history of thrombocytopenia with autosomal dominant inheritance, macrothrombocytopenia and in this particular case, due to the response to thrombopoietin receptor agonist, eltrombopag.We report a 51 years old female who had a first episode of thrombocytopenia ad 23 years of age during a pregnancy. At the age of fifty, a hysterectomy was indicated due to a metrorrhagia: a platelet count of 21000/ul was detected. She was treated with eltrombopag with a good response. A family history of the patient revealed the presence of thrombocytopenia in several family members. Suspecting a hereditary thrombocytopenia, a genetic study revealed a mutation in the MYH-9 gene. This mutation can be suspected when there is a family history of thrombocytopenia with autosomal dominant inheritance, macrothrombocytopenia and in this particular case, due to the response to thrombopoietin receptor agonist, eltrombopag.