A growth model based on chemical kinetics for vapour phase epitaxy of silicon by pyrolysis of silane (SiH4) in a horizontal rectangular reactor at atmospheric pressure has been developed. The model incorporates the dependence of growth rate on various physical and geometrical parameters such as temperature, flow rate, mole fraction, position and angle of tilt. The model has been tested against such experimental data as are available in the literature and satisfactory agreement has been observed. An interesting feature of the model is that it predicts the growth rate to be fairly independent of the position of the susceptor within the reactor when the angle of tilt is 1.5°. The model has been coded in a simple computer program. © 1990.