The author prepared various Pt complexes of 1,2-cyclohexanediamine(=dach) by the modification of the leaving groups. In order to prepare water-soluble Pt (1R,2R-dach) complexes, mono and bis(D-glucuronato) (1R,2R-dach) Pt complexes were prepared. They were very soluble in water, showing high antitumor activity and Pt(D-glucuronato) (1R,2R-dach). NO₃ (l-GHP) was attempted to develop clinically, but it showed side effect in pancreas by the subacute toxicity test and l-GHP was not developed. The author prepred Pt (IV) complexes of PtCl₂ (lR,2R-dach), Pt(ox) (1R,2R-dach) and Pt (mal) (1R,2R-dach). They became water soluble and showed higher activity. In order to prepare liposoluble Pt (1R,2R-dach) complexes, the author prepared tetra-O-acetyl-α(β)-D-glucuronate complexes. Pt(Ac₄-glucuronato) (1R,2R-dach). NO₃ was soluble in water and chloroform, while Pt(Ac₄-glucuronato)₂ (1R,2R-dach) was not soluble in water, but soluble in organic solvents. The author also prepared vitamin and steroid containing Pt(1R,2R-dach) complexes as organ specific antitumor Pt complexes, and they showed higher antitumor activity. Among the Pt (1R,2R-dach) complexes prepared, Pt (oxalato) (1R,2R-dach) is one of the best antitumor Pt complexes and it is developed now in Europe clinically, being effective against melanoma, breast, ovary and testis cancers, as well as cis-Platin resistant tumors.