The present clinical study was designed to evaluate the efficacy, pharmacokinetics and safety of a new 10% liquid intravenous immune globulin in patients with primary immunodeficiency diseases. Sixty-one adults and children with primary immuno-deficiency diseases received doses of 300-600 mg/kg body weight every 21-28 days for 12 months. No validated acute serious bacterial infections were reported. The 95% confidence interval for the annualized rate of acute serious bacterial infections (primary endpoint) was 0-0.060. A total of four predefined validated other bacterial infections commonly occurring in primary immunodeficiency disease subjects were observed; none were serious, severe or resulted in hospitalization. The median elimination half-life of IgG was 35 days. Median total IgG trough levels varied from 9.6 to 11.2 g/L. Temporally associated adverse experiences were determined for 72 h after each infusion and the most common adverse experience was headache, which was associated with 6.9% of infusions. The study met the primary endpoint for efficacy and demonstrated excellent tolerability of the new 10% liquid intravenous imunoglobulin preparation.