In this review article, we discuss and analyze the validities of centrifugal sudden (CS) approximations in chemical reactions, with emphasis on the recent progress in the comparison studies of close-coupling and CS approximations in chemical dynamics both adiabatically and nonadiabatically. All these relevant studies are performed using the time-dependent wave packet approach, focusing on several typical and benchmark chemical reactions, for example, the triatomic adiabatic ion-molecule reactions of Ne + H-2(+), He + HeH-, O- + H-2, O+ + D-2, and O+ + HD, the triatomic nonadiabatic reactions of N+NH and O+N-2, and the tetraatomic and polyatomic adiabatic reactions of H-2 + D-2 and H + CHD3. (C) 2015 Wiley Periodicals, Inc.