An impregnating resin for an electrical insulation body includes a base resin, a filler having nanoscale particles, and a radically polymerizing reactive diluent. The impregnating resin includes a crosslinker for crosslinking the base resin and the reactive diluents. The base resin is an epoxy resin. An electrical insulation body includes the impregnating resin and a method produces the electrical insulation body by production of an impregnating resin having a base resin, a filler having nanosize particles and a free-radically polymerizing reactive diluent.