A series of novel water-soluble amine platinum (II) tellurate complexes of the type (A)Pt(II) [TeO2(OH)4], where A = 1,2-diaminocyclohexane (DACH), 1,1-bis(aminomethyl)cyclohexane (AMCH), ethylenediamine (en), or cyclopentylamine (cpa), were prepared either by the reaction of amineplatinum (II) sulfate with barium tellurate or by a direct reaction of (A)Pt(OH)2 with telluric acid. Oxidation of the amine platinum(II) tellurate produced amine platinum(IV) tellurate (A)Pt(IV)trans(Z) [TeO2(OH)4] complexes, where Z = OH or Cl, following oxidation with hydrogen peroxide or with chlorine gas, respectively. Complexes were characterized by elemental analysis, and IR and 195Pt NMR spectroscopy. Against i.p. murine leukemia cells in vivo, some of the complexes displayed good antitumor activity when administered intraperitoneally (i.p.) on days 1, 5, and 9 at their optimal doses. Pt(II) complexes containing R,R-DACH, S,S-DACH, R,R-S,S-DACH, or AMCH produced %T/C of 147 to 288 whereas cis-DACH, en, and cpa complexes were inactive. In the Pt(IV) series, the R,R-DACH complex with axial Cl was highly active (%T/C = 371, 40% cures) compared with the complex with axial OH (%T/C = 135).