Several new 3‐(isoxazol‐3‐yl)‐quinazolin‐4(3H)‐one derivatives were synthesized and tested for their analgesic and antiinflammatory activities, as well as for their acute toxicity and ulcerogenic effect. A few compounds were as active as phenylbutazone in the writhing and acetic acid peritonitis tests. They had a very low ulcerogenic effect.