The potential drop and the self-heating due to the contact resistance at the interface between silicide and silicon are incorporated in the device simulation for ESD protection devices. A transition region is provided at the interface and the resistivity is calculated by scaling the contact resistance by the length of the region. The power density used in the heat conductive equation is calculated by using the potential drop and the contact resistance in the transition region. The validity of the present approach is checked by the Monte Carlo simulations. Using the technique, influence of the contact resistance on self-heating in an ESD protection device with the grounded gate MOSFET structure is simulated.