The aim of this work is to use molecular modeling methods to predict the possible biological target of the 1,2,3-triazole hybrid molecules and using in silico methods to determine the site and the way of binding of active compounds to the selected target. Antiproliferative activity of eight hybrid 1,2,3-triazole derivatives were tested on five different tumor cell lines, and all of them have shown antiproliferative effect in vitro, with significant cytostatic activity. Between N, N-1,3-bis(1,2,3-triazole)-5-bromouracil hybrids p-fluoro(1), o-fluoro(3) and pchlorophenyl( 2) substituted 1,2,3-triazoles which showed a strong inhibitory effect on HepG2 and HeLa cell line growth. Inhibition of cell proliferation was observed in the presence of micromolar concentration of tested compounds. The inhibition of the cell proliferation was even stronger if compared with the inhibition of the same cells under the same conditions in the presence of the reference substance of 5-fluorouracil. No mitochondrial toxicity was observed for compounds tested. In addition to above mentioned methods, the PASS analysis was used to make predictions of possible biological targets for tested compounds. The selection of the biological target(s) was based on the structure of compounds and on known structure of biological macromolecules from protein bases. PASS analysis predicted that strong antitumor activity of compounds 1, 2, and 3 is due the inhibition of the Wee1 tyrosine kinase. Using the Autodock Vina program and in silico screening, compounds 2 and 3 were docked to Wee1 kinase crystal structure downloaded from the protein database [PDB: 5v5y]. Molecular fit analysis has shown that compounds 2 and 3 specifically bind to the pocket of ATP binding site of Wee1 kinase, and that the binding domain of the tested compounds is the same as the binding site of specific inhibitor of Wee1 kinase MK-1775 (IC50 = 5,2 nM). Cytostatic effects of compounds 2 and 3 can be attributed to the inhibition of the G2-M control of the cell cycle, which is a control point of Wee1 kinase. In addition, compounds 2, 3, and MK-1775 have shown decreased phosphorylation of the isolated proteins by Western blot after the stimulation of peripheral mononuclear cells. Considering that the cyclin-dependent kinase Cdk1 is one of the major substrates for Wee1 kinase, molecular modeling and in silico docking has been undertaken to better explain the influence of Wee1 kinase activity on phosphorylation of Cdk1 kinase.