Excitonic carrier dynamics taking place in InxGa1-xN/GaN multi-quantum-well systems have been studied by low temperature picosecond time resolved photoluminescence (LT-TRPL), HR-TEM, XPS, Dynamic TOF-SIMS, and quantum mechanical simulation methods. Both time-integrated and time-resolved photoluminescence spectra of InxGa1-xN/GaN multi-quantum-wells with different well thickness and Indium composition were measured at 10 K. We assigned the natural radiative lifetime of each sample from the time resolved PL. We observed that the natural radiative lifetime of In InxGa1-xN/GaN multi-quantum-wells depends strongly on the well thickness and Indium composition. To support the measured natural radiative lifetimes, excitonic oscillator strengths of the InxGa1-xN/GaN multi-quantumwells were calculated by using a 2-D particle-in-a-box model as functions of well thickness and Indium composition. Values of the well thickness and Indium compositions from the HR-TEM and XPS compositional depth profiling were used to achieve more realistic computational results and to corroborate the measured natural radiative lifetimes of InxGa1-xN/GaN multi-quantum wells.