Abstract To test the anti-human immunodeficiency virus type-1 (HIV-1) activity of 3,6,9,12-tetraazatetradecane-1,14-diylbis(zinc dithiocarbamate)- S,S ′-dioxide (cyclic zinc-dithiocarbamate- S,S ′-dioxide), MAGI and MAGIC-5 cells were used; the former express CXCR4 and the latter express both CXCR4 and CCR5, which are HIV-1 coreceptors. The compound markedly inhibited HIV-1 X4 (CXCR4-using) viral replication in both MAGI and MAGIC-5 cells. On the other hand, the replication of HIV-1 R5X4 (both CXCR4-and CCR5-using) in MAGI cells but not MAGIC-5 cells was inhibited by the compound. The compound was found to specifically inhibit HIV-1 (X4) envelope-mediated cell-to-cell fusion, binding of anti-CXCR4 monoclonal antibody (12G5) to CXCR4 expressed on the surface of cells, and calcium flux induced by stromal-derived factor-1α (SDF-1α) bound to CXCR4. The results suggest that the compound inhibited CXCR4-mediated HIV-1 infection by influencing to the HIV-1 coreceptor activity of CXCR4.