Biometal salts form with alkylated thiosemicarbazones biologically active coordination compounds with various composition and structure. The structure, physicochemical and biological properties of these substances are determined by the nature of the central atom and its ligand surroundings.  Therefore, the aim of this work is the synthesis, determination of structural features and antitumor activity  of diiodo-{methyl-N-prop-2-en-1-yl-n-[1-(pyridine-2-yl)ethylidene]carbamohydrazonothioate}zinc  ZnLI2 (I). Complex (I) was obtained in ethanolic solution by the reaction between zinc iodide and 2acetylpyridine 4-allyl-Smethylisothiosemicarbaz one (L) taken in 1:1 molar ratio. Monocrystals of this substance were obtained by recrystallisation from ethanol.  It was determined that in complex I one molecule of L and two iodide-ions are coordinated. The coordination polyhedron of the zinc atom is a distorted tetragonal pyramid. The base of this pyramid is formed by pyridinic and azomethinic nitrogen atoms, sulfur atom of the isothiosemicarbazone L and one iodine atom. The fifth coordination place is occupied by another iodine atom. The coordination by methylated sulfur atom is an unusual case. In literature sources such coordination way is found rarely and only on other central atoms [1]. The study of antitumor properties of the complex I showed that it inhibits growth and proliferation of human promyelocytic leukemia HL-60 cells in the range of concentration  10-5 -10-7M. At the concentration 10-5 mol/L it inhibits 91%, at the 10-6 mol/L - 83% and  at 10-7 mol / L - 12% of tumor cells. This work was fulfilled with the financial support of the Institutional Project 15.817.02.24F.