More and more publications can be found in recent years where detailed models are employed to describe the chemical and molecular transport processes controlling flame structure. Up to a recent past, such studies were restricted to simple zero- or one-dimensional laminar computations, like ignition in a fully premixed mode, freely propagating laminar premixed flames or counter-flow flames. Since such models are now often used to investigate turbulent flames in multi-dimensional computations, we feel it is useful to review the literature on this subject and give a synthesis of the obtained results. To be more specific, we consider only in this review publications where (1) chemical processes are modeled with a multi-step reaction scheme, taking at least an intermediate species into account; or (2) molecular diffusion processes of the individual species are represented by a more elaborate model than assuming unity Lewis numbers; and (3) the retained configuration leads to unsteady strain-rate and curvature (or stretch-rate) variations in the reaction zone. Over 200 recent publications have been found to respect these criteria. Summarizing the results, one can say that there appears to be a growing need for simulations relying on detailed models for chemistry and transport processes, probably due to the fact that restrictions concerning pollutant emissions motivate a request for more accurate, quantitative results. Progress must still be accomplished concerning the identification of chemical pathways, the accurate determination of rate constants, and the development of reliable but efficient chemistry reduction techniques. The impact of the retained molecular diffusion model is higher than expected at the beginning of this study. Even for turbulent configurations, the global impact of these models can be comparable to switching between two different detailed chemical schemes. Concerning local flame structure, the transport models play an essential role, in particular for high flame curvatures and far from stoichiometry. As a whole, the need for matching the accuracy level of the chosen chemical and transport models is emphasized, since describing a physical phenomenon in great detail while, at the same time, representing another phenomenon of comparable importance with a very rough model, prevents really quantitative (and even perhaps qualitative) predictions. Specific difficulties concerning validation are also identified. (C) 2003 Elsevier Ltd. All rights reserved.