Laser annealing of shape memory alloy thin films provides new opportunities in actuator design and fabrication for microelectromechanical systems applications. In this paper, we present a three-dimensional thermal model to simulate the crystallization process when a laser beam is swept across an amorphous NiTi thin film. Experimental crystallite nucleation and growth rates are included in the model to enable prediction of the size of the crystallized region as a function of laser annealing parameters. The model can also be used to study the crystallization of other material systems by means of laser annealing.