The practice of passive immunization with human immune globulin (IG) for the control of communicable diseases (measles, rubella and hepatitis A) differs somewhat between Australia, the United States of America, the United Kingdom, and New Zealand despite the many similarities of these countries, including disease incidence rates and population immunity. No minimum effective dose of IG has been identified for protecting susceptible contacts of measles or hepatitis A. Recommended passive immunisation practice for susceptible pregnant contacts of rubella is based on limited evidence in all countries. We suggest that gaps in the evidence base need to be addressed to appropriately inform the role of passive immunisation in public health practice into the future.