Abstract: The invention relates to an ignition system for a multi-cylinder Otto-type four-stroke engine equipped with at least one spark plug per cylinder, the ignition system including for each spark plug an ignition device (61, 62) connectible to said spark plug in the engine substantially without cables, the ignition system also incorporating a control unit (8) sending signals in response to the engine operating conditions for triggering sparks at the spark plugs in a predetermined order. In order to ensure, in such ignition systems, transmission of maximum ignition voltage to the engine spark plugs and enable simple and safe handling of the ignition system during service and the like, the invention is mainly distinguished in that the ignition devices (61, 62) to at least two adjacent spark plugs are included in a common, handleable unit, a so-called ignition cassette (70).