Heterocyclic compounds comprise the leading and most diverse family of organic compounds. A huge number of heterocyclic derivatives are proved to be pharmacologically active and are also in regular clinical use to be efficient drugs. This book describes the diverse nature of physicochemical and pharmacological properties of derivatives of some heterocycles including s-triazine quinazoline quinoline coumarin piperazine oxadiazole as well as thiazolidinone and some structural motifs like chalcone schiff base thiourea semicarbazide etc.