Biopharma Plasma LLC is recruiting for a phase III trial to assess the safety and efficacy of intravenous immunoglobulin (company: Bioven) in treating chronic primary ITP in adults. Participants must be between 18-65 years old and have chronic primary ITP (>12 months since diagnosis) with a platelet count <30x109/L. Participants taking corticosteroids may be enrolled if the treatment dose has been stable for at least 2 weeks prior to enrolment. Individuals who received transfusions of IVIG in the previous 1 month, are intolerant to plasma preparations, pregnant, had splenectomy, or other blood disorders other than ITP will be unable to participate. Individuals who received other experimental ITP therapies, such as Rituximab, in the prior 3 months will not be able to participate.