The synthesis of chalcone system -C=C-C=O is relatively easy to prepare, usually highly reactive and are starting point of preparation of various bioactive compounds. This α,β-unsaturated ketones (chalcones) can be synthesized by Claisen-Schmidt condensation of different aromatic aldehydes with ketone and their cyclization with hydrazine hydrate in basic condition. Numerous pyrazoline derivatives have been found to possess considerable biological activities, which stimulated the research activity in this field. Amongst all the nitrogen containing five member heterocycles, it have proved to be the most useful framework for biological activities and have attracted attention of medicinal chemists for both with regard to heterocyclic chemistry and the pharmacological activities associated with them. We have synhtesized some chalcones and pyrazolines and have studied their antimicrobial activity.