In this study, the dynamic instability analysis of rotating delaminated thickness tapered composite plates with different taper configurations subjected to periodic in-plane loads is performed. The governing differential equations of motion of the various configurations of a rotating thickness mid-plane delaminated tapered laminated composite plate are presented in the finite element formulation based on classical laminated plate theory including various rotational effects. The finite element formulation developed for the dynamic instability analysis of rotating delaminated tapered composite plate is validated by comparing the parametric exciting frequencies evaluated using the present finite elementmethod (FEM) with those presented in available literature and comparing the natural frequencies of rotating delaminated tapered composite plate evaluated using the present FEM with experimentally measured results. Various parametric studies are also performed to study the effect of taper configurations, rotational speed, delamination length, delamination location and in-plane periodic loads on stability of the structure. It was seen that the influences of rotating speed on the principalDIR spectra among taper configurations and uniform plate are significant and the normalized width of principal and second instability regions of parametric resonance frequencies increase in the order of uniform, TC3, TC2 and TC1 for all the rotating speeds. © Springer-Verlag Berlin Heidelberg 2016.