Abstract: The invention relates to a breakerless ignition system with a magneto supply for use in an internal combustion engine. The system includes a transistorized circuit for interrupting the current flow in the primary winding of the coil to thereby produce the firing voltage in the secondary which is connected to the spark plug. The circuit includes either a single transistor, or two transistors in a Darlington arrangement, connected in series in the circuit of the primary winding. A switching transistor is connected to the control electrode of either the first transistor or the Darlington pair to be adaptable to turn it off. A first resistor has one end connected to the base of the switching transistor. A parallel resistor-capacitor combination is connected in series with a further resistor, and the serial combination is connected in parallel with the Darlington arrangement or the single transistor.