The reactivities of β-aziridinylcinnamaldehyde and β-(2-methylaziridinyl)acrylaldehyde with respect to amines, hydrazines, and semicarbazide were studied, β-Aminoacroleins were obtained by reaction of secondary amines with aziridinylacroleins. The reaction of aziridinylcinnamaldehyde with primary amines gives the corresponding imines. It was established that in its reaction with hydrazines and semicarbazide aziridinylacrolein is more inclined to undergo heterocyclization reactions (the formation of pyrazoles and pyrazolines) than aziridinylcinnamaldehyde.