Abstract: This invention relates to an internal combustion engine having an exhaust system provided with probes for exhaust gas analysis. The exhaust system comprises plurality of exhaust ducts attached to and communicating with respective engine cylinders, individual ducts into which said exhaust ducts discharge at least in pairs and one exhaust pipe into which said exhaust ducts discharge. There are provided at least two probes, at least one of which is disposed in one of said ducts upstream of said exhaust pipe, whereas another probe is disposed either in said exhaust pipe or in one of said ducts. Said probes are connected to suitable devices for controlling the physical quantities relating to the operation of the engine.