New N-substituted amides of 3-(3-ethylthio-1,2,4-triazol-5-yl)propenoic acid (2-12) were designed and prepared by the condensation reaction of exo-S-ethyl-7-oxabicyclo-[2.2.1]-hept-5-ene-2,3-dicarbonyl isothiosemicarbazide (1) with primary amines. The chemical structure of all compounds was confirmed by IR, (1)H NMR, (13)C NMR spectra, the X-ray crystallography (for compounds 8, 11, 12) and elemental analysis. Moreover, compounds 9-11 were screened for their anticancer activity. Compounds 9 (in concentrations of 0.32 mM and 0.16 mM), 10 (in concentrations of 0.28 mM and 0.14 mM), and 11 (in concentrations of 0.35 mM and 0.17 mM) were found to be evidently effective in vitro against lung cell line (IC50). The distinctly marked antiproliferative effect of compounds 9 and 10 in breast carcinoma cells in vitro was ascertained. Moreover, the lowest cytotoxicity of compound 9 in concentrations of 0.16 mM and 0.03 mM against the normal skin fibroblast cell line and breast carcinoma cell in vitro after 24- and 48-h periods of incubation was noticed in this study.