A fuel supply control system for an internal combustion engine having at least one fuel injection valve for injecting fuel into an intake pipe or a combustion chamber of the engine. A flow rate of air supplied to the engine and an air-fuel ratio are detected. A demand fuel injection amount is set according to an operating condition of the engine. An injection amount command value of fuel injected by at least one fuel injection valve according to the demand fuel injection amount. An amount of fuel burned in the engine is calculated according to the detected intake air flow rate and air-fuel ratio. At least two correlation parameters, which indicate a relationship between the estimated burned fuel amount and the injection amount command value, are identified. The injection amount command value is then corrected according to the at least two identified correlation parameters.