 This is a phase II open-label study. Patients will be screened for MPN diagnoses and patients with Polycythemia vera proven to have JAK2V617F mutation will be given the option to enroll. Consenting patients will take erlotinib daily for 16 weeks. Blood work and pharmacokinetics will be drawn for serum level monitoring. Doses will be administered according to side effects or held. First assessment will be at day 15 wth subsequent assessments at 28 day intervals. Non-responders will be taken off the study and managed according to standard of care. Patients who do respond will continue taking the therapy for a total of 12 months. Observation will be for a total of 12 months after finishing treatment. In addition to the clinical aspect of this study, there will be correlative studies where molecular response will be checked and its correlation with clinical response. 