Behavior of gold in the Si/SiO2 interface region has been investigated using deep level transient spectroscopy (DLTS) in the MOS structures made on p-type silicon wafers with orientation. The results are as follows. A new defect, Au-Hit(0.445), has been observed at the interface, which is the incorporation of gold atom by the interaction with the interface defect, Hit(0.494). A continuous spectrum of the interface states related to gold has also been measured in the lower half of Si band gap, which are acceptors, and the physical mechanism of the positive shift of the flat band voltage of the MOS structure caused by gold doping ean be explained in terms of these gap states. The profile of the gold donors in the silicon near the interface has been obtained, which is not monotonically increase towards the surface but exhibits a maximum at 0.37μm from the surface.