RegioExpress, commonly abbreviated to RE, is a category of fast regional train service in Switzerland, run by Swiss Federal Railways (SBB CFF FFS) or other railway companies (such as TILO, BLS, tpf, THURBO or RhB, previously also by transN). A few lines also serve stations in Germany, France and Italy. Since 2023, all RE services are numbered for more clarity. Some of them are named.
It is comparable to the Regional-Express in Germany, Austria and Luxembourg. Its speed is considerably faster than regional trains at the same level, as it does not stop at all stations served by the regional trains. Nonetheless, it is slightly slower than InterRegio trains. Swiss Federal Railways describes the trains as ones that serve "rapidly into the regions".