The experimental conditions and procedure for quantitative analysis of steel by laser-induced breakdown spectroscopy in argon at atmospheric pressure using an infrared Nd:YAG laser have been studied. Satisfactory analytical results have been obtained for the determination of C, Si, Cr, and Ni contents in low-alloyed steels. The lens-to-sample distance is shown to be a relevant parameter, which can be selected at each pulse energy to enhance the line intensities and the repeatability of measurements. A higher precision has been obtained for line-intensity ratios (0.9–2.5% relative standard deviation for concentrations higher than 0.1%) than for absolute intensity measurements. The calibration curves for all the elements have correlation coefficients above 0.999. Detection limits are in the range 6–80 ppm.