<p>JAK2V617F is the major driver mutation in polycythemia vera, and detection of this mutation is one of the most important keys for the diagnosis of this disease. In addition, JAK2V617F mutation is highlighted as a molecular marker for monitoring treatment. Clinical studies of the JAK inhibitor ruxolitinib and two recently introduced new forms of alfa interferon, pegylated interferon alfa 2b and ropeginterferon alfa 2b, demonstrated that treatment with these agents induced a molecular response, defined as a more than 50% reduction in the JAK2V617F allele burden from baseline, in approximately 60% of patients. In addition, some patients achieved a complete molecular response, defined as the disappearance of the mutation. More importantly, achievement of a molecular response was positively correlated with improved thrombosis-free and progression-free survival in PV patients. To date, controlling hematological parameters, especially maintaining hematocrit levels below 45%, has been the gold standard surrogate endpoint in PV treatment. With new treatment options and knowledge, molecular response should be incorporated as a new therapeutic surrogate endpoint in the management of PV.</p>