Abstract: A lateral bipolar transistor with a doped zone of a small lateral width can be obtained by means of a method for manufacturing a lateral bipolar transistor with a collector region and a base region in a SOI wafer slice with an insulating layer, a silicon layer over the insulating layer, with a protective coating of oxide over the silicon layer, with trenches through the protective layer and the silicon layer as far as the insulating layer with substantially lateral walls, which are bounded by substantially lateral faces of the protective coating and the silicon layer, by implanting dopants in the silicon layer, in which the implantation takes place on one of the substantially lateral faces of the silicon layer.