The effects of turbulence and flame instabilities on the flame front evolution at Lewis number (Le) 1.0 and 0.7 were computationally investigated using a sixth-order central difference scheme and nonreflective boundary conditions. The turbulence intensity varies from 1% to 50% and the resulting turbulent flames are in the thin wrinkled flame region. It is shown that when the turbulence intensity is weak (u(')=1%-5%), hydrodynamic instability dominates the growth of the flame cells. However, when the turbulent intensity is large (u(')=50%), the turbulent motion wrinkles the flame front and dominates the evolution process. It is also demonstrated that curvature stretch dominates the total stretch rate for flames with either weak or large turbulent intensities, and therefore plays a significant role in turbulent flame modeling. (c) 2006 American Institute of Physics.