The molecular structure of the title compound, a steroidal isoxazolidine derivative, which is formed by transannular nitrone 1,3-dipolar cycloaddition in the reaction of (Z)-3beta-acetoxy-5,10-secocholest-1(10)-en-5-one with N-methylhydroxylamine, was determined by X-ray analysis, confirming the 1(2)-position of the double bond and the presence of a cis-3beta,5beta-epoxyimino bridge.