Raman measurements of C2H2 and CO mole fractions in a laminar axisymmetric methane-air diffusion flame are compared with numerical predictions. A high-repetition-rate, high-average-power laser is used to increase signal-to-noise ratio to measure these minor flame species. Computationally, the system of governing equations including detailed chemistry and transport is solved by a damped modified Newton's method. The calculations predict the measured temperature and nitrogen mole fractions quantitatively. While there is agreement within experimental uncertainty between calculated and measured acetylene concentrations, the calculations predict sharper C2H2 gradients on the lean side of the radial profiles. Adjusting rate of the reaction between C2H2 and OH to values derived in recent experimental and theoretical studies has only a minor impact on the calculated C2H2 profiles. The numerical simulations describe the CO profiles qualitatively, underpredicting the measured CO mole fraction by 40%. (C) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.