A new series of 2-(6-oxo-3,5-diphenyl-GH-pyridazin-1-yl)-acetamides and 3-[6-oxo-3,5-diphenyl-6H-pyridazin-1-yl)-propanamides were synthesized and evaluated in terms of their analgesic and anti-inflammatory activities. All compounds except for 7g were more potent than aspirin in a p-benzoquinone-induced writhing test at 100 mg/kg dose. Compounds 7b, 7c and 7e had the highest anti-inflammatory activity; compound 7e was the Most potent in terms of analgesic and anti-inflammatory activities and had no ulcerogenic side effects.