Nitric oxide emission control is one of the major problems encountered in the development of combustion chambers for all types of applications. Scaling rules describing the dependence of NO, emission on operating parameters such as pressure, mixture ratio or turbulence intensity provide useful design guidelines. While such rules are well established for thermal NO, much less is available for prompt NO. This specific problem is considered in this article. The influence of pressure and strain rate on prompt NO production is investigated experimentally in a laminar counterflow diffusion flame. The results relative to the pressure dependence compare well with complex chemistry calculations in well-stirred reactors. The strain rate dependence is in good agreement with previous theoretical results found in the literature. The scaling established for the laminar flame is then applied to a turbulent nonpremixed combustor in order to describe the influence of strain on prompt NO production. The results are analyzed on the basis of a decomposition between global chemical effects and local effects due to strain. The final expression given for the prompt NO scaling in the turbulent diffusion flame provides a good correlation of experimental measurements.