Treatment with intravenous human immunoglobulin (IVIG) has become a routine therapeutic method in immu- nodeficiency states and autoimmune diseases. Although it is a relatively safe therapeutic method it may have serious undesirable effects. Knowledge of these undesirable effects is the prerequisite for coping with them and in some instances it is possible to prevent them. Undesirable effects of IVIG administration can be divided into six groups: 1. Generalized reaction, in particular fever, shiver, nausea, vomiting, tachycardia, dyspnoea, changes of blood pressure are recorded in less than 5% patients, usually during infusion and depend on the rate of administration. 2. Hypersensitivity and anaphylactic reactions may be also severe to fatal and are usually the manifestation of the action of antibodies against IgA; they may be anticipated in particular in patients with deficiency of class A immunoglo- bulins and in patients with autoimmune diseases. 3. Haematological: rare and usually clinically irrelevant haemolytic anaemia. 4. Neurological: frequent and minor headache, rarely relapsing aseptic meningitis syndrome. 5. Nephro- logical: renal failure which developed by the mechanism of osmotic nephrosis, relatively very rare, affecting almost exclusively patients with nephropathy present before administration of IVIG. 6. Thrombotic complications mani- fested by cerebral ischaemia. They are however extremely rare and their relationship to IVIG administration is controversial. At present we can rule out transmission of viral infection by IVIG preparations with the exception of transmission of the hepatitis C virus.

        Key words: intravenous human immunoglobulin, undesirable effects, autoimmune diseases.