Regioselective 1,3-dipolar cycloaddition of nitrilimines with 5-arylidene-2-arylimino-4-thiazolidinones and with 2-(4-arylidene)thiazolo[3,2-a]benzimidazol-3(2H)-ones afforded the corresponding 1,3,4-triaryl-5-N-arylpyrazole-carboxamides and pyrazolylbenzimidazoles. All reactions were carried out under conventional thermal heating and/or microwave irradiation. Both the pyrazole-5-carboxamides and pyrazolylbenzimidazoles were examined for their in-vitro anti-tumor activities against two tumor cell lines, Hep-2 and colon CaCo-2. Most of the obtained compounds exhibited significant activity against CaCo-2 and Hep-2 cell lines.