Two series of pyridazinone derivatives (19-34) were synthesized and evaluated for antitubercular activities against Mycobacterium tuberculosis H37Rv strain. The results illustrated that among the synthesized compounds, compound 25, 5-(4-hydroxy-3-methoxybenzyl)-3-(4-chloro-phenyl)-1,6-dihydro-6-pyridazinone emerged as a lead compound with good antitubercular activity. Four more compounds, (21, 22, 29 & 33) were significant in their antitubercular action.