An analysis is made of the phenomenon of structural transition which g
eneralizes the phase transition concept and encompasses structures of
all levels and strong nonequilibrium. The main properties, the laws go
verning structural transitions, and the effects caused by them are ind
icated. A simple model is proposed to describe structural transition a
nd is used to analyze various nonequilibrium transitions. (C) 1998 Ame
rican Institute of Physics. [S1063-7850(98)01502-X].