In heterocyclic chemistry, amidoximes are mostly known as precursors for the synthesis of 1,2,4-oxadiazoles. Indeed, most of the works related to the use of amidoximes in the synthesis of heterocycles are devoted to 1,2,4-oxadiazoles. Nevertheless, such an artificial narrowing of the scope of heterocyclic systems that can be obtained through amidoximes is not justified. These readily available derivatives can serve as convenient starting compounds not only for 1,2,4-oxadiazoles, but also for imidazoles and imidazolines, benzoxazoles, pyrimidines, 1,2,4-oxadiazines, and other heterocycles, including condensed. This review reveals the great synthetic potential of amidoximes in heterocyclic chemistry.