Microstructural transformations in 304 L stainless-steel welds as a function of welding parameters were studied using a high-power continuous CO2 laser. The experimental results can be represented by the relation lambda1 = 40 V-1/2 where lambda1 is the primary dendrite spacing in mum and V is the welding speed in mm s-1, for different laser powers and two sample thicknesses. The cooling rates estimated by different methods have been found to be in the range 10(2) to 3 x 10(3) K s-1, and the temperature gradients are in the range 10(2) to 9 X 10(2) K cm-1. The experimental results are shown to be in very good agreement with recent dendrite-growth models. An analogy is presented between the cooling rate during melt spinning and laser welding.