Condensation of 5-methyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one with p-hydroxybenz-aldehyde in alcoholic sodium hydroxide yielded (Z)-4-(4-hydroxybenzylidene)-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one which was treated with acetylacetone, hydrazine hydrate, ethyl cyanoacetate, and ethyl acetoacetate to afford pyranopyrazole, pyrazolopyrazole, pyrazolopyridine, and 6-aminopyrazolopyridine derivatives, respectively. 5-Methyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one was also reacted at the enamino carbon atom with 2,4-dichlorobenzoyl isothiocyanate, thiosemicarbazide, and hydrazine hydrate to produce pyrazoloxazine, pyrazolopyrazole, and spiro[pyrazole-3,3′-pyrazolo[3,4-c]pyrazole] derivatives.