An experimental study was conducted in a constant volume combustion chamber for investigation of the flame propagation characteristics in the presence of non-homogeneous concentration distributions of the fuel-air mixture. Different levels of non-homogeneity of the fuel-air mixture distributions were produced by the reciprocating movements of a pair of perforated plates. By independent control of the mixture distribution and the turbulence intensity, the effects due purely to the mixture heterogeneity and those due to the turbulence under non-homogeneous mixture distributions on the flame propagation speed and the flame shape were investigated in detail. Results from direct photography of the flame propagation processes showed that flames in the non-homogeneously distributed mixtures are corrugated, and can propagate faster than those in the homogeneous mixtures at the same level of turbulence. An optimal mixture distribution for maximum flame propagation exists among the different non-homogeneously distributed mixtures.