Pipobroman is an anti-cancer drug that probably acts as an alkylating agent. Pipobroman has well documented clinical activity in polycythemia vera (PV) and essential thrombocythemia (ET). Pipobroman allows, within 3 months, to attain a response in more than 90% of patients, without clinically relevant toxicities. The 10-years risk of thrombosis of patients treated with Pipobroman is about 15%, The anti-proliferative activity of Pipobroman on bone marrow megakaryocytes seems of particular value in lowering the occurrence of post-PV and post-ET MMM, whose risk is the lowest registered with available treatments. The 10-year risk of acute leukemia with Pipobroman is 5% in PVand 3% in ET, which is only slightly higher than that expected as a natural evolution of the disease. In conclusion, the use of Pipobroman is a definite alternative to hydroxyurea in patients with PV and ET at high risk of thrombosis.