Abstract 1-Phenyl-3-methyl-5-pyrazolone-4-oxime reacted with benzylamine, methylamine, methyl-and ethyl ioides to give 3-methyl-1, 5-diphenyl-1H-, 3-methyl-1-phenyl-1H-and 3, 5- dimethyl-1-phenyl-1H-pyrazolo [4, 3-d] oxazoles I, II. The structure of I was elucidated authentically through other routes by interaction of 1-phenyl-3-methyl-4, 5-dioxopyrazolone with benzylamine and/or benzaldehyde and ammonium acetate. Various 3-meth-yl-5-aryl- ...