The invention concerns a bipolar transistor with an epitaxially grown base and a self-positioned emitter, whereby the base is formed from a first substantially monocrystalline epitaxial region (1) which is arranged in parallel relationship to the surface of the semiconductor substrate (2) and a second substantially polycrystalline and highly doped region (3) of the same conductivity type which is arranged in perpendicular relationship to the substrate surface and encloses the first region at all sides and that said second region, at least at one side but preferably at all four sides, is conductingly connected to a third, preferably highly doped or metallically conducting, high temperature-resistant polycrystalline layer (4) which is arranged in parallel relationship to the surface of the semiconductor substrate and forms or includes the outer base contact to a metallic conductor track system.