Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 9028, Jeddah 21413, Saudi Arabia Manuscript received 18 May 1990, revised 22 October 1990, accepted 28 November 1990 Fourteen heterocyclic furyl and thienyl chalcones (5) were prepared, analysed and converted Into the 2-pyrazolines (6) through treatment with hydrazine or methyl- bydrazine in ethanol or glacial acetic acid solvent. A total of thirty new furyl and thienyl substituted-2-pyrazolines (11a-f, 12a-f, 13a-f,14a-e 15a-g) were thus prepared and characterised through elemental and spectroscopic measurements Mechanistic interpretation of the results is also included