Intravenous immunglobulin (IVIg) is used to treat a number of immune-deficiences and autoimmune diseases. Safety concerns related to a number of reported thromboembolic complications prompted us to review the literature. These complications happened mainly in individuals that had risk factors for thromboembolism, like advanced age, previous thromboembolic diseases, bed-ridden, and in individuals in which high doses or high infusion rates of IVIg were administered. The mechanism responsible for these events seems to be a rise in plasma viscosity that can trigger a thromboembolic event, especially in cases in which there is an underlying circulation impairment. Complications can be minimized by using IVIg only in clear-cut indications, weighting risk versus benefit in patients who are at high risk for thromboembolism and by sticking to carefully monitored slow infusion rates. IVIg for the treatment of autoimmune disorders should be administered as a five-day course of 2 g/kg of body weight. Each daily dose of 400 mg/kg should be given in not less than eight hours.