At the present time special attention is given to biological aspects of coordination chemistry. It was found that coordination compounds of some 3d-metals with derivatives of 2formylpyridine 4-phenylthiosemicarbazone inhibit the growth and proliferation of human myeloid leukemia cells, prostate cancer cells, and breast cancer cells. The antitumor activity of studied coordination compounds depends on the nature of the moiety in the forth position of the corresponding thiosemicarbazide. The aim of this work is the synthesis, determination of the composition, structure, and antitumor activity of the coordination compounds of nickel and copper with isatin β-(N-pyridin2-yl)thiosemicarbazone (HL). The synthesis of the isatin β-(N-pyridin-2-yl)thiosemicarbazone was done according to the scheme: The experiments showed that chlorides of stated above metals react with synthesized thiosemicarbazone HL in ethanol solution in 1:1 molar ratio forming fine-crystalline compounds of different colors and composition: MX2 · nH2O +m HL→ M(HL)X2 (I - M= Cu, X= Cl-; II - M= Ni, X= Cl-) The magnetochemical research showed that the synthesized coordination compounds are paramagnetic. Copper coordination compound Cu(HL)Cl2 is monomeric because its effective magnetic moment at room temperature correspond to spin value for one unpaired electron. Antitumor activity of synthesized compounds was studied at the Centre hospitalier universitaire de Quebec (CHUQ), Canada. Isatin β-(N-pyridin-2-yl)thiosemicarbazone (HL) inhibits the proliferation of human promyelocytic leukemia HL-60 cells only at the concentration 10-5 mol/l. Coordination of the thiosemicarbazone (HL) to the biometal ions increases the antitumor activity. The nickel coordination compound shows antitumor activity even at the concentration 10-7 M.