A brief description is given of the Frascati storage ring design for electron-positron colliding beam experiments. Electrons and positrons of 250 Mev each are stored in a d-c weak-focusing magnet. They circulate on the same orbit meeting in the gap of the radio-frequency and in the neighborhood of three other points on the orbit at 90 deg from each other. The particles are produced by converting the gamma rays of the Frascati electron synchrotron on two targets placed inside the acceleration chamber and alternately exposed to the beam. (T.R.H.)