An electronic ballast for gas discharge lamps has a rectifier (1) that can be connected to a voltage supply source, a condenser circuit which is connected to the rectifier and consists of a first capacitor (2) and a second capacitor (3), a series circuit which is connected to the capacitor connections and consists of a first controllable switch (4) and a second controllable switch (5) which can be alternately switched, and a load circuit which is connected to the connection point between the first and second switches and consists of a series resonance circuit composed of a resonance inductance (6) and of a resonance capacitor (7), as well as of a gas discharge lamp (8) connected thereto. In addition, a transformer is provided whose first winding (9) is connected to the connection point between the first and second capacitor (2, 3) and whose second winding (10) is connected to the resonance capacitor (7).