Abstract: A process for rehabilitating sewer pipes whereby a plurality of plastic pipes made of thermoplastics is inserted into a sewer pipe, closing off any incoming house drain inlets, and is subsequently connected to the house drain inlets. For this purpose the position of the house drain inlet in the area closed off by the plastic piping is located, and a through-hole is created in the plastic pipes in the area in which they close off the house drain inlet. The size of the through-hole is at least equal to the projection of the cross-section of the house drain pipe. A saddle-type branch fitting, having a pipe segment member and a pipe socket integral therewith and outwardly extending therefrom, is placed in the closed-off area so that the pipe socket projects into the house drain inlet via the through-hole. The pipe segment member is secured to the plastic pipe in the area of contact.