Vortex Induced Vibrations (VIVs) of circular cylinders is a complex phenomenon encountered in many engineering fields such as marine and civil applications. This paper presents experimental and Computational Fluid Dynamic (CFD) simulation results for group of four cylinders, arranged in 2�2 rectangular arrays, subjected to VIVs. The physics involved in VIV is not fully understood, especially when a cylinder is falling in the wake of another cylinder. The objective of this study is to determine the effect of center to center spacing between the cylinders on VIV forces and response amplituds. The CFD simulation was conducted using Large Eddy Simulation (LES) method. The model test was carried out in the offshore engineering laboratory at Universiti Teknologi PETRONAS, Malaysia. The range of Reynolds (Re) Number achieved in the present study varied between 4.96E+03-2.48E+04. The comparison of the results shows that CFD simulations outcome is in good agreement with the experimental results. © 2016 Taylor & Francis Group, London.