In our previous study we reported that synthesis of ethyl (6-substituted-3(2H)-pyridazinon-2-yl)acetate derivatives which showed potent analgesic and anti-inflammatory activities. In the present paper, as an extension of our earlier work, we described acid I Va-h and amide Va-h analog of ethyl (6-substituted-3(2H)-pyridazinon-2-y) acetate derivatives. Except for IVa, all compounds were synthesized for the first time in this study. The chemical structures of newly synthesized compounds were elucidated by their IR, 1H-NMR spectral data, and elementary analysis. The compounds were screened for their analgesic and antiinflammatory activities, acute toxicity and ulcerogenic effect. Some compounds showed significant analgesic and antiinflammatory activities and at the same time, nil ulcerogenic effect. Among the (6-substituted-3(2H)-pyridazinon-2-yl) acetic acid IV derivatives the best activity was presented by I Ve and IVg derivatives.