The original work of the present book consists of three research projects: In the first part: Synthesis, cytotoxicity evaluation, molecular docking and utility of novel chalcones as precursors for heterocycles incorporating pyrazole moiety.In the second part: Synthesis and antimicrobial activity of novel azolopyrimidines and pyrido-triazolo-pyrimidinones incorporating pyrazole moiety.In the third part: Synthesis of new pyrazolyl-pyridines as antitumor agents. The assigned structures for all the newly synthesized compounds were confirmed on the basis of elemental analyses and spectral data and the mechanisms of their formation were also discussed. In addition, some of the newly synthesized chalcones were tested for their cytotoxicity against human colon carcinoma cell line (HCT-116) and against human hepatocellular carcinoma (HEPG2) cell lines and the results revealed that some compounds have promising activities compared with the standard drug Doxorubicin. Molecular docking was also carried out for the high potent compounds.