Abstract: The modular multizone heater system is for controllably heating areas of a structure, for example for bonded doubler reparation. The system comprises a number of heater cells to be placed in thermal contact with the areas to be heated of the structure. Each heater cell has a heating element and a temperature sensor. The heating elements of the heater cells are connected to a heater power supply to receive electric power. The heater power supply is controlled by a control unit receiving control data from a computer. The temperature sensors of the heater cells are connected to the control unit that relays the temperature data produced by the temperature sensors to the computer for monitoring, processing and control purposes.