Growth morphology transitions of austenite during solidification of a laser remelted Fe-C-Si alloy have been studied by theoretical modeling and laser remelting experiments. A synthetic cast iron with 1.7 wt% C and 4.3 wt% Si was remelted using laser scanning velocities ranging from 5 x 10(-5) to 2 x 10(-1) m/s. Three different austenite morphologies have been found: planar, cellular and dendritic. A transition from planar to cellular solid/liquid interface of the austenite crystals is observed at a solidification velocity of 30 mu m/s. Another morphological transition between cells and dendrites is observed at 1.5 mm/s growth velocity. The experimental results of transition velocities have shown good agreement with theoretical values. The primary dendrite spacing in the laser remelted zone is also evaluated and compared with the theoretical predictions.