Abstract
This study applies multiple-capture models to drug treatment data and the synthetic estimation method to arrestee data to provide estimates of the number of IVDUs in Los Angeles County in 1989. Based on the 5% HIV-prevalence rate currently found in IVDUs in Los Angeles, it is estimated that there could be as many as 9,500 HIV-infected IVDUs. The estimates of IVDUs are generally higher than those obtained by back-calculation methods which often undercount IVDU-related AIDS cases and do not consider deaths for causes other than HIV infection.