Four novel series of pyrazolyl-4(3H)-quinazolinones have been prepared through the reaction of 3-aryl-2-hydrazino-4(3H)-quinazolinones with antipyrylazo-derivatives of ethyl acetoacetate, acetylacetone or diethyl malonate. These series of compounds are 3-aryl-2-[1-ethoxycarbonyl-1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H - pyrazol-4-yl)hydrazono-2-propylidene]hydrazino-4(3H)-quinazo linones; 3-aryl-2-[4-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl) hydrazono-3-methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl]-4(3H)-quinaz olinones; 3-aryl-2-[4-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)azo -3,5- dimethyl-1H-pyrazol-1-yl]-4(3H)-quinazolinones and 3-aryl-2-[4-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl) hydrazono-3,5-dioxo-pyrazolidin-2-yl]-4(3H)-quinazolinones. The antiinflammatory activity of some representatives of the prepared compounds was studied.