Chosen parameters assessing neutrophil function (myeloperoxidase – MPO concentration, elastase concentration, phagocytic test and oxygen metabolism of neutrophils) in 38 year old patient diagnosed with CVID are presented. The examinations were carried out before the first infusion of IVIG and on the second day after infusion. Before IVIG substitution increased MPO serum concentration was found, enhanced total phagocytic skills and strongly suppressed oxygen metabolism of neutrophils measured by the chemiluminescency test. IVIG substitution improved both spontaneous and stimulated neutrophil chemiluminescence (CL).