In this work, some pyridazinones were studied for their cardioactive activity. These compounds showed significant cardio-active action with respect to the regular used drugs. However, it was found that the existence of the pyridazine ring is a crucial necessity in the structure of these pyridazinonecompounds to show the improved cardioactive activities. It was also understood that the substitution of the different group on the pyridazinone ring with other related bioisosteres or isosteres along with the existence of pyridazine ring may provide better cardioactive compounds. Pyridazinoneis, a component of various cardio-active agents, which are in uses clinically or in clinical trials. These contain pimobendan, indolidan, levosimendan, imazodan, CI-930, meribendan, bemoradan, senazodan, siguazodan, amipizone, prinoxodan, Y-590, SK&F-93741, SKF 95654, NSP-805, NSP-804 and KF 15232. This study briefly reviews the pyridazinone ring for the progress of new cardio-active drugs.