Resistance to arsenic compounds was examined among amikacin resistant Gram-negative bacteria isolate from a hospital environment. Arsenite resist,lnce (Ars’) was found in a high proportion of isolates ( > 60%) being frequently associated with resistance to tellurite (40%), and to other antimicrobial agents. Ars determinants (27%) were found to be transferable to E. coli K12 strains from which large plasmid DNA molecules were isolated and characterized by agarose gel electrophoresis. Plasmids were identified by both classical incompatibility tests, and by replicon typing using DNA specific probes. Most of the amikacin-arsenite (AkkArsIl conjugative plasmids belong to the H incompatibility group. These results suggest that Ak-Ars resistance linked to IncH plasmids is wide spread in Gram-negative bacteria. 0 1997 Elsevier Science B.V.Institute de Medicina Experimental(IME), Facultad de Medicine,Instituto de Biologia Experimental (IBE), Facultad de Ciencias, Universidad Central de Venezuela