Strong effect of steel hardness on the parameters of laser-induced plasma (e.g., temperature) and on the calibration curves for manganese and chromium in steels has been demonstrated. The presence of the inverse correlation between the steel hardness and the excitation temperature determined by Mn I lines was explained by the confinement of laser plasma with the crater walls. A new calibration strategy based on the summation of intensities for several lines of the analyte allowed one to reduce the effect of matrix, caused by mechanical properties, on the determination of chromium and manganese in steels. The advantages of this strategy are discussed in the article in comparison with the wellestablished approaches, such as an internal standard and single analytical line.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.