In this paper. we present the electromagnetic compatibility (EMC) analysis of a telecommunication building struck by a direct lightning stroke based on a simulation model. For this purpose, the resulting magnetic and electric fields have been determined as a function of time considering potential points where lightning is expected to strike. These potential points correspond to places where highly susceptible equipment is installed in the telecommunication building. For illustration purposes, electromagnetic interference inside a telecommunication building is calculated using the newly proposed three-dimensional cell model and finite difference discretization technique. Some illustrations are presented to point out the advantages of the proposed electromagnetic interference prediction model used during the design of the electrical and electronic installations by considering the lightning effects. Finally, examples of electric and magnetic fields inside the building as well as lightning-induced over voltages due to side return stroke were given at various distances in the simulation results. (C) 2004 Elsevier B.V. All rights reserved.