Randomness in any composite structure is inevitable. Randomness in fiber arrangement and constituent material properties for a metal matrix composite are considered, with both fiber and matrix being isotropic. Finite Element Analysis has been done with the assistance of Probabilistic Design module of ANSYS. Random samples has been generated using Latin Hyper-Cube Sampling technique. Three sets of simulation were carried out. In the first simulation, only the fiber arrangement was varied. In the second simulation, only the material properties of the constituents were varied. In the third simulation, both fiber arrangement and material property were varied. The results show that when randomness in both fiber arrangement and constituent material property were considered the elastic constants of composite show wide variation. There is appreciable uncertainty in the composite material properties and the converged effect is not a trivial extrapolation of input probability distributions. Also, various material constants of the composite are affected to differing extent.