Inclusion Criteria:

Subjects will be eligible for study entry if they:

• are at least 18 years old
• have a form of primary immunodeficiency (PID) as described by Rosen et al, 1999 16 manifesting as agammaglobulinemia (X-linked) or hypogamma-globulinemia (common variable immunodeficiency), requiring immunoglobulin replacement therapy
• have had regular treatment for at least three months with either intravenous immunoglobulin preparations or immunoglobulin preparations for intramuscular use given subcutaneously
• have serum IgG levels greater than or equal to 5 g/L as determined by the local laboratory at screening
• if female of childbearing potential, agree to employ adequate birth control measures during the study
• have given written informed consent

Exclusion Criteria:

Subjects will not be eligible for study entry if they:

• had severe adverse reactions to treatment with immunoglobulin preparations during the last three treatments before inclusion into the study
• suffer from documented selective IgA deficiency with antibodies against IgA
• have an acute infection that requires intravenous antibiotic treatment (Last treatment day should be seven days before study entry.)
• are known to be infected with HIV, HCV, or HBV
• are at high risk of contracting blood-borne viral infections through parenteral drug abuse or life style
• suffer from congestive heart failure and receive on-demand treatment with furosemide
• show renal dysfunction defined as serum creatinine greater than or equal to 1.5 mg/dL at baseline visit
• received another investigational drug in the three weeks preceding study entry
• in case of females, are pregnant or nursing mothers