Background: In light of the limited supply of intravenous immunoglobulins, it is important to strive for their appropriate use. Off-label use needs to be discouraged because of the limited supply of intravenous immunoglobulins, their unproven effectiveness in many conditions, their high costs, and the risk of adverse effects. This study aims to document the use of intravenous immunoglobulins in registered and off-label conditions in Belgian hospitals. Methods: Data were derived from the IMS Health hospital disease database. For each condition, this database generated figures about the number of patients and the reimbursement value in 2007. Data were provided at the level of individual products. Results: In 2007, intravenous immunoglobulins were administered to 9,629 patients, amounting to a reimbursement value of EUR 33.5 million (or 17% of Belgian hospital drug expenditure). Around 50–60% of intravenous immunoglobulin use was associated with registered conditions and around 40–50% with off-label use, depending on how use was measured. Off-label use occurred in unspecified conditions, surgery, orthopedics and oncology. There was limited use in myasthenia gravis. The market was dominated by Multigam and Sandoglobuline, each of which made up 45–50% of intravenous immunoglobulin use. Conclusions: In addition to their use in registered conditions, intravenous immunoglobulins are used off-label in other conditions in Belgium. A number of options are proposed to discourage off-label use in light of the limited supply of intravenous immunoglobulins, their unproven effectiveness in many conditions, their high cost, and the risk of adverse effects.