Relationships between the local heat release rate and CH concentration have been investigated by numerical simulations of methane-air premixed flames and simultaneous CH and OH PLIF (planar laser-induced fluorescence) measurement has been also conducted for lean cellular premixed flame as well as for laminar flames. The distance between the peak of heat release rate and that of CH concentration is less than 91 mu m for all equivalence ratios calculated. Even for the premixed flame in high intensity turbulence, the distribution of the heat release rate coincides with that of CH mole fraction. For CH PLIF measurements, CH fluorescence intensity in terms of equivalence ratio shows a similar trend with CH mole fraction computed by GRI mechanism even in lean conditions. These results imply that CH PLIF measurements can be applicable to the estimation of the spatial fluctuations of heat release rate in the turbulent premixed flame. (C) 2006 Elsevier B.V. All rights reserved.