This Book is mainly useful for students, research scholars and pharmaceutical industrialists who have taken introductory course to understand the importance of Heterocyclic compounds, it’s biological properties such as antibacterial, antifungal, anthelmetic, insecticidal activities & the spectral studies of Pyrazoline, 4-thiazolidinone and their 5-arylidine, 2-azetidinone and isoxazolines derivatives.