Various pthalazine derivatives have been synthesized and tested for their diverse biological activities. Pthalazine derivatives have been exhibited pharmacological activities like antitumor, PARP-1 inhibitors, antimicrobial, antivirus, antihistamine-H1, antiallergic rhinitis, antifungal, anti-inflammatory, anti-proliferative, COX-2 inhibitor, LOX-5 inhibitor, antidiabetes, and other biological activities like imaging agent. Pthalazine derivatives were also used as agrochemicals and chemicals. Various synthetic aspects indicate that pthalazines derivatives are easy to synthesize which can produce a wide variety of activity.