ObjectivesTo improve the quality of surveillance data for HIV in Victoria by following up all cases with an unknown exposure category; and to determine whether those with no exposure category included cases of transmission other than via the conventionally recognised routes.MethodsThe Victorian HIV database records data on all people diagnosed with HIV in Victoria, including information on route of exposure to the virus. We identified all HIV diagnoses to which no exposure category had been attributed and, with the permission of the State Minister for Health, obtained access to namecoded testing records. Exposure categories, where possible, were obtained directly from these records. Otherwise, cases were checked against the namecoded AIDS database and, if necessary, an intensive process of call‐back to laboratories, diagnosing doctors and HIV treatment centres was undertaken.ResultsThe database initially contained records for 289 people with unknown exposure categories (9.1% of Victorian people with HIV infection). We identified exposure categories for 155 of these people.ConclusionsExposure categories for those cases previously without data were similar to those for cases where exposure category was known. No instances of HIV transmission by previously unrecognised means were detected.