[Figure not available: see fulltext.] This review contains a generalized and systematically arranged data about thermal, photochemical, and catalytic transformations of isoxazole–2-carbonyl-2H-azirine that were published in the period from 1969 to 2015, and considers the possibilities for using these compounds in the synthesis of nitrogen heterocycles. Radical and pericyclic steps of isomerization reactions have been discussed. Density functional theory calculations of the relative thermodynamic stability of isomeric isoxazoles and azirines have been performed. A total of 76 references are given.