Individual case reports have documented nephrotoxicity of intravenous immunoglobulin (IVIG) preparations, but the true incidence of renal dysfunction is unknown and many data sheets do not include renal impairment as a side-effect of these preparations. We determined the incidence of renal impairment in an unselected cohort of patients receiving two different preparations of IVIG over 20 months, administering 287 courses of IVIG to 119 patients for a variety of indications, including thrombocytopenia, systemic lupus erythematosis, neuropathy, Guillain-Barre syndrome and infections. Two different preparations of IVIG were used, Vigam (BPL) and Sandoglobulin (Novartis), which differ in the concentration of sucrose added as a stabilizer. Eight patients showed deterioration in renal function (6.7%), and in two, no renal recovery occurred (1. 7%). There were no significant differences in the patient characteristics or dose or preparation of IVIG administered to those patients with or without changes in serum creatinine. There was no association between the amount of sucrose in the IVIG and development of renal failure. IVIG (regardless of the sucrose content) is associated with renal impairment which may be irreversible, with a maximum incidence of 6.7%. All patients should have their renal function monitored during the use of IVIG.