The purpose of this study is to determine the pharmacokinetics, efficacy and safety of Immune Globulin Intravenous (Human), 10% TVR (Triple Virally Reduced) Solution in subjects with primary immunodeficiency (PID) manifesting as hypo- or agammaglobulinemia. Subjects are treated every 21 days and receive a total of 12 infusions: for the first 3 infusions subjects receive GAMMAGARD S/D to ensure a steady-state and to acquire data with a licensed product; for the remaining 9 infusions subjects receive IGIV, 10% TVR Solution.