A control system for an internal combustion engine having fuel injectors for injecting fuel into a combustion chamber of the engine. A fuel property is estimated based on a combustion state of the fuel injected into at least one cylinder of the engine. The fuel injectors are controlled so that a specific amount of fuel is injected into the at least one cylinder and an amount of fuel corresponding to an operating condition of the engine is injected into cylinders other than the at least one cylinder. An additional fuel injection is performed after the fuel injection of the specific amount with respect to the at least one cylinder, for example, when a torque difference parameter indicative of a difference between a torque generated by the at least one cylinder and a torque generated by the other cylinders is equal to or greater than a predetermined threshold value.