4-Mono- and 4,4-disubstituted-3-imino-2-benzoyl-5-pyrazolones have been prepared from the corresponding ethyl mono- or disubstituted cyanoacetates and N-benzoylhydrazine. The presence of the imino group in 4,4-disubstituted-3-imino-2-benzoyl-5-pyrazolones was ascertained by the hydrolysis of 4,4-dibenzyl-3-imino-2-benzoyl-5-pyrazolone into 4,4-dibenzyl-3-oxo-2-benzoyl-5-pyrazolone. In order to prove that the benzoyl group in these pyrazolones was not in Position 1, the synthesis of 4-benzyl-3-amino-1-benzoyl-5-pyrazolone was attempted from 4-benzyl-3-carbethoxy-1-benzoyl-5-pyrazolone through a Curtius degradation of the 3-carbethoxy substituent into a 3-amino group. It was found that the 1-benzoyl group was hydrolyzed at the same time as the 3-carbethoxyamino substituent. The ultraviolet absorption spectra of all these compounds are reported and discussed briefly.