A series of organometallic and inorganic drugs has been synthesized at the CSIRO Division of Chemicals and Polymers. The drugs, which are all polyanions of various size, shape and charge are being tested for their activity for the HIV virus in a continuous human T-lymphocyte line (MT2) and in peripheral blood lymphocytes (PBLs). Determinations of drug activity have been carried out at the Fairfield Hospital's Virology Department. It is important for the drug synthesis programme to develop an understanding of the relationship between polyanion properties and antiviral activity. For this it is essential to establish: (a) whether polyanions enter HIV infected cells, (b) their distribution within these cells, (c) whether this distribution is the same for all polyanions, (d) whether the drugs remain intact (do not dissociate) on entering the cell, (e) the differences between active and inactive drugs of similar structure. Answers to these questions and to others will facilitate the synthesis programme.