The book covers the literature on synthetic and biological importance of pyrazolopyrimidine and fused pyrazolopyrimidine derivatives. Synthesis of Some new pyrazolopyrimidines and fused pyrazolopyrimidines has been discussed with synergism of alternative innovative synthetic techniques such as PTC, Microwave solvent free heating and Pd catalysis. Molecular docking and in vitro antimicrobial investigations have been included to show their biological importance.