Some 1-(4-arylthiazol-2-yl)-3,5-diaryl-2-pyrazoline derivatives were synthesized by reacting 1-thiocarbamoyl-3,5-diaryl-2-pyrazoline derivatives with phenacetylbromide in ethanol. The structural elucidation of the compounds were performed by IR, H-1-NMR and Mass spectral data and elemental analyses. The hypotensive activities of 13 compounds were evaluated by using the tail-cuff method. All examined compounds showed appreciable hypotensive activities. Clonidine was used as reference substance in the pharmacological evaluation. (C) 2000 Editions scientifiques et medicales Elsevier SAS.